Oracle PL/SQL Tutorial/Table/Alter Table
Содержание
- 1 Adding a Column
- 2 ADD initially_created DATE DEFAULT SYSDATE NOT NULL;
- 3 Altering a Table
- 4 alter table nologging
- 5 Alter table to add new constraint for new added column
- 6 Alter table to add primary key
- 7 Alter table to add primary key across more than one columns
- 8 Alter table to add primary key with tablespace and storage setting
- 9 Alter table to add unique with tablespace and storage setting
- 10 ALTER TABLE to DISABLE a CONSTRAINT
- 11 Changing the Data Type of a Column
- 12 Changing the Default Value of a Column
- 13 Changing the Precision of a Numeric Column
- 14 Changing the Size of a Column
- 15 Decrease the length of a column
- 16 Decrease the precision of a numeric column
- 17 Dropping a Column
- 18 Fill data into new added table column
- 19 New added columns are empty
- 20 Some of the aspects of a column you can modify using ALTER TABLE
Adding a Column
<source lang="sql">
SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> ALTER TABLE employee
2 ADD modified_by INTEGER;
Table altered. SQL> SQL> desc employee;
Name Null? Type ------------------------------------ ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15) MODIFIED_BY NUMBER(38)
SQL> SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION MODIFIED_BY
---------- ---------- --------- --------- ---------- ---------- --------------- -----------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL></source>
ADD initially_created DATE DEFAULT SYSDATE NOT NULL;
<source lang="sql">
SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> ALTER TABLE employee
2 ADD initially_created DATE DEFAULT SYSDATE NOT NULL;
Table altered. SQL> SQL> desc employee;
Name Null? Type --------------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15) INITIALLY_CREATED NOT NULL DATE
SQL> SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION INITIALLY
---------- ---------- --------- --------- ---------- ---------- --------------- ---------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02-JUN-07 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 02-JUN-07 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 02-JUN-07 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 02-JUN-07 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 02-JUN-07 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 02-JUN-07 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 02-JUN-07 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 02-JUN-07 8 rows selected. SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL></source>
Altering a Table
You alter a table using the ALTER TABLE statement.
You can use ALTER TABLE to perform tasks such as:
- Add, modify, or drop a column
- Add or drop a constraint
- Enable or disable a constraint
6. 3. Alter Table 6. 3. 1. Altering a Table 6. 3. 2. <A href="/Tutorial/Oracle/0120__Table/SomeoftheaspectsofacolumnyoucanmodifyusingALTERTABLE.htm">Some of the aspects of a column you can modify using ALTER TABLE</a> 6. 3. 3. <A href="/Tutorial/Oracle/0120__Table/AddingaColumn.htm">Adding a Column</a> 6. 3. 4. <A href="/Tutorial/Oracle/0120__Table/ADDinitiallycreatedDATEDEFAULTSYSDATENOTNULL.htm">ADD initially_created DATE DEFAULT SYSDATE NOT NULL;</a> 6. 3. 5. <A href="/Tutorial/Oracle/0120__Table/ChangingtheSizeofaColumn.htm">Changing the Size of a Column</a> 6. 3. 6. <A href="/Tutorial/Oracle/0120__Table/Decreasethelengthofacolumn.htm">Decrease the length of a column</a> 6. 3. 7. <A href="/Tutorial/Oracle/0120__Table/ChangingthePrecisionofaNumericColumn.htm">Changing the Precision of a Numeric Column</a> 6. 3. 8. <A href="/Tutorial/Oracle/0120__Table/Decreasetheprecisionofanumericcolumn.htm">Decrease the precision of a numeric column</a> 6. 3. 9. <A href="/Tutorial/Oracle/0120__Table/ChangingtheDataTypeofaColumn.htm">Changing the Data Type of a Column</a> 6. 3. 10. <A href="/Tutorial/Oracle/0120__Table/Filldataintonewaddedtablecolumn.htm">Fill data into new added table column</a> 6. 3. 11. <A href="/Tutorial/Oracle/0120__Table/ChangingtheDefaultValueofaColumn.htm">Changing the Default Value of a Column</a> 6. 3. 12. <A href="/Tutorial/Oracle/0120__Table/Altertabletoaddnewconstraintfornewaddedcolumn.htm">Alter table to add new constraint for new added column</a> 6. 3. 13. <A href="/Tutorial/Oracle/0120__Table/ALTERTABLEtoDISABLEaCONSTRAINT.htm">ALTER TABLE to DISABLE a CONSTRAINT</a> 6. 3. 14. <A href="/Tutorial/Oracle/0120__Table/Altertabletoaddprimarykey.htm">Alter table to add primary key</a> 6. 3. 15. <A href="/Tutorial/Oracle/0120__Table/Altertabletoaddprimarykeyacrossmorethanonecolumns.htm">Alter table to add primary key across more than one columns</a> 6. 3. 16. <A href="/Tutorial/Oracle/0120__Table/DroppingaColumn.htm">Dropping a Column</a> 6. 3. 17. <A href="/Tutorial/Oracle/0120__Table/Newaddedcolumnsareempty.htm">New added columns are empty</a> 6. 3. 18. <A href="/Tutorial/Oracle/0120__Table/Altertabletoadduniquewithtablespaceandstoragesetting.htm">Alter table to add unique with tablespace and storage setting</a> 6. 3. 19. <A href="/Tutorial/Oracle/0120__Table/Altertabletoaddprimarykeywithtablespaceandstoragesetting.htm">Alter table to add primary key with tablespace and storage setting</a> 6. 3. 20. <A href="/Tutorial/Oracle/0120__Table/altertablenologging.htm">alter table nologging</a>
alter table nologging
<source lang="sql">
SQL> SQL> SQL> create table big_table as select * from all_objects where 1=0; Table created. SQL> SQL> set autotrace on statistics; SQL> SQL> insert into big_table select * from all_objects where rownum < 50; SQL> insert /*+ APPEND */ into big_table select * from all_objects where rownum < 50;
SQL> commit; Commit complete. SQL> alter table big_table nologging; Table altered. SQL> insert into big_table
2 select * from all_objects where rownum < 50;
49 rows created.
SQL> insert /*+ APPEND */ into big_table
2 select * from all_objects where rownum < 50;
49 rows created.
SQL> commit; Commit complete. SQL> SQL> drop table big_table; Table dropped. SQL> SQL></source>
Alter table to add new constraint for new added column
<source lang="sql">
SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL primary key, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
-------------------- -------------------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
desc employee;
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
-------------------- -------------------- --------- --------- ---------- ---------- ---------------
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> alter table employee
2 add ( 3 gender varchar(10) 4 );
Table altered. SQL> SQL> alter table employee
2 add constraint ck_gender
3 check (gender in ("MALE", "FEMALE"));
Table altered. SQL> SQL> SQL> SQL> desc employee;
Name Null? Type -------------------------------------------------------------------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15) GENDER VARCHAR2(10)
SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped.</source>
Alter table to add primary key
<source lang="sql">
SQL> SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> ALTER TABLE employee
2 ADD PRIMARY KEY (id);
Table altered. SQL> SQL> SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped.</source>
Alter table to add primary key across more than one columns
<source lang="sql">
SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> SQL> ALTER TABLE employee
2 ADD PRIMARY KEY (id, 3 first_name, 4 last_name 5 );
Table altered. SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped.</source>
Alter table to add primary key with tablespace and storage setting
<source lang="sql">
SQL> SQL> create table employee_job (
2 id number not null, 3 worker_id number not null, 4 logical_workplace_id number not null, 5 active_date date default SYSDATE not null, 6 inactive_date date ) 7 tablespace USERS pctfree 20 8 storage (initial 10K next 10K pctincrease 0);
Table created. SQL> SQL> SQL> alter table employee_job add
2 constraint employee_job_PK 3 primary key ( id ) 4 using index 5 tablespace USERS pctfree 20 6 storage (initial 10K next 10K pctincrease 0);
Table altered. SQL> SQL> drop table employee_job; Table dropped. SQL></source>
Alter table to add unique with tablespace and storage setting
<source lang="sql">
SQL> SQL> create table employee_job (
2 id number not null, 3 worker_id number not null, 4 logical_workplace_id number not null, 5 active_date date default SYSDATE not null, 6 inactive_date date ) 7 tablespace USERS pctfree 20 8 storage (initial 10K next 10K pctincrease 0);
Table created. SQL> SQL> SQL> alter table employee_job add
2 constraint employee_job_UK 3 unique ( 4 worker_id, 5 active_date ) 6 using index 7 tablespace USERS pctfree 20 8 storage (initial 10K next 10K pctincrease 0);
Table altered. SQL> SQL> SQL> SQL> drop table employee_job; Table dropped. SQL> SQL></source>
ALTER TABLE to DISABLE a CONSTRAINT
<source lang="sql">
SQL> SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL primary key, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> SQL> ALTER TABLE employee
2 ADD CONSTRAINT reasonable_stock_date CHECK(
3 start_date >= to_date("19000917","YYYYMMDD")
4 );
Table altered. SQL> SQL> SQL> ALTER TABLE employee DISABLE CONSTRAINT reasonable_stock_date; Table altered. SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped.</source>
Changing the Data Type of a Column
If the table is empty or the column contains null values, you can change the column to any data type.
Otherwise you can only change the data type of a column to a compatible data type.
<source lang="sql">
SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> SQL> desc employee;
Name Null? Type ----------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> ALTER TABLE employee
2 MODIFY first_Name CHAR(15);
Table altered. SQL> SQL> desc employee;
Name Null? Type ------------------ ID NOT NULL VARCHAR2(4) FIRST_NAME CHAR(15) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL></source>
Changing the Default Value of a Column
The default value only applies to new rows added to the table.
<source lang="sql">
SQL> CREATE TABLE myTable (
2 id INTEGER, 3 status VARCHAR2(20) DEFAULT "Order placed" NOT NULL, 4 last_modified DATE DEFAULT SYSDATE 5 );
Table created. SQL> SQL> desc myTable;
Name Null? Type ------------------- ID NUMBER(38) STATUS NOT NULL VARCHAR2(20) LAST_MODIFIED DATE
SQL> SQL> SQL> ALTER TABLE myTable
2 MODIFY last_modified DEFAULT SYSDATE - 1;
Table altered. SQL> SQL> desc myTable;
Name Null? Type -------------------- ID NUMBER(38) STATUS NOT NULL VARCHAR2(20) LAST_MODIFIED DATE
SQL> SQL> drop table myTable; Table dropped. SQL></source>
Changing the Precision of a Numeric Column
<source lang="sql">
SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE), 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> desc employee;
Name Type -------------------- ID VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> ALTER TABLE employee
2 MODIFY salary NUMBER(8,4);
Table altered. SQL> SQL> desc employee;
Name Type -------------- ID VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,4) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL></source>
Changing the Size of a Column
<source lang="sql">
SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> ALTER TABLE employee
2 MODIFY first_name VARCHAR2(30);
Table altered. SQL> SQL> SQL> desc employee;
Name Null? Type ---------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(30) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
------------------------------ ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL></source>
Decrease the length of a column
You can only decrease the length of a column if there are no rows in the table or all the columns contain null values.
<source lang="sql">
create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
no rows selected SQL> SQL> SQL> desc employee;
Name Null? Type -------------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> SQL> ALTER TABLE employee
2 MODIFY first_name VARCHAR2(3);
Table altered. SQL> SQL> SQL> desc employee;
Name Null? Type ----------------------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(3) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> select * from Employee
2 /
no rows selected SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL></source>
Decrease the precision of a numeric column
You can only decrease the precision of a numeric column if there are no rows in the table or the column contains null values.
<source lang="sql">
SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
no rows selected SQL> SQL> SQL> desc employee;
Name Null? Type -------------------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> ALTER TABLE employee
2 MODIFY salary NUMBER(2,2);
Table altered. SQL> SQL> desc employee;
Name Null? Type ------------------ ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(2,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> select * from employee; no rows selected SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL></source>
Dropping a Column
<source lang="sql">
SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
---------- ---------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> desc employee;
Name Null? Type ----------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) LAST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> ALTER TABLE employee
2 DROP COLUMN last_name;
SQL> SQL> desc employee;
Name Null? Type ----------------- ID NOT NULL VARCHAR2(4) FIRST_NAME VARCHAR2(10) START_DATE DATE END_DATE DATE SALARY NUMBER(8,2) CITY VARCHAR2(10) DESCRIPTION VARCHAR2(15)
SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL></source>
Fill data into new added table column
<source lang="sql">
SQL> SQL> SQL> SQL> -- create demo table SQL> create table Employee(
2 ID VARCHAR2(4 BYTE), 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 /
Table created. SQL> SQL> -- prepare data SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values ("01","Jason", "Martin", to_date("19960725","YYYYMMDD"), to_date("20060725","YYYYMMDD"), 1234.56, "Toronto", "Programmer")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("02","Alison", "Mathews", to_date("19760321","YYYYMMDD"), to_date("19860221","YYYYMMDD"), 6661.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("03","James", "Smith", to_date("19781212","YYYYMMDD"), to_date("19900315","YYYYMMDD"), 6544.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("04","Celia", "Rice", to_date("19821024","YYYYMMDD"), to_date("19990421","YYYYMMDD"), 2344.78, "Vancouver","Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("05","Robert", "Black", to_date("19840115","YYYYMMDD"), to_date("19980808","YYYYMMDD"), 2334.78, "Vancouver","Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("06","Linda", "Green", to_date("19870730","YYYYMMDD"), to_date("19960104","YYYYMMDD"), 4322.78,"New York", "Tester")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("07","David", "Larry", to_date("19901231","YYYYMMDD"), to_date("19980212","YYYYMMDD"), 7897.78,"New York", "Manager")
3 /
1 row created. SQL> insert into Employee(ID, First_Name, Last_Name, Start_Date, End_Date, Salary, City, Description)
2 values("08","James", "Cat", to_date("19960917","YYYYMMDD"), to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", "Tester")
3 /
1 row created. SQL> SQL> SQL> SQL> -- display data in the table SQL> select * from Employee
2 /
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
-------------------- -------------------- --------- --------- ---------- ---------- ---------------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION
-------------------- -------------------- --------- --------- ---------- ---------- ---------------
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> alter table employee
2 add ( 3 gender varchar(10) 4 );
Table altered. SQL> SQL> alter table employee
2 add constraint ck_gender
3 check (gender in ("MALE", "FEMALE"));
Table altered. SQL> SQL> SQL> update employee
2 set gender = "MALE" 3 where mod(id,2) = 0 4 /
4 rows updated. SQL> SQL> select * from employee;
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION GENDER
-------------------- -------------------- --------- --------- ---------- ---------- --------------- ----------
01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester MALE 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager MALE 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester MALE 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager
ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION GENDER
-------------------- -------------------- --------- --------- ---------- ---------- --------------- ----------
08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester MALE 8 rows selected. SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL></source>
New added columns are empty
<source lang="sql">
SQL> create table employee(
2 employee_id number(9), 3 first_name varchar2(15), 4 last_name varchar2(20), 5 email varchar2(25), 6 constraint pk_employee primary key (employee_id) 7 );
Table created. SQL> SQL> insert into employee
2 values (1, "Tom", "Kyte", "t@aaa.ru");
1 row created. SQL> SQL> insert into employee
2 values (2, "Sean", "Dillon", "s@aaa.ru");
1 row created. SQL> SQL> insert into employee
2 values (3, "Christopher", "Beck", "c@aaa.ru");
1 row created. SQL> SQL> commit; Commit complete. SQL> SQL> select *
2 from employee;
EMPLOYEE_ID FIRST_NAME LAST_NAME EMAIL
-------------------- -------------------- -------------------------
1 Tom Kyte t@aaa.ru
2 Sean Dillon s@aaa.ru
3 Christopher Beck c@aaa.ru
3 rows selected. SQL> alter table employee
2 add ( 3 phone_number varchar2(10) 4 ) 5 /
Table altered. SQL> SQL> select *
2 from employee;
EMPLOYEE_ID FIRST_NAME LAST_NAME EMAIL PHONE_NUMB
-------------------- -------------------- ------------------------- ----------
1 Tom Kyte t@aaa.ru
2 Sean Dillon s@aaa.ru
3 Christopher Beck c@aaa.ru
3 rows selected. SQL> drop table employee; Table dropped. SQL> SQL></source>
Some of the aspects of a column you can modify using ALTER TABLE
The following list shows some of the aspects of a column you can modify using ALTER TABLE:
- Change the size of a sizable column, such as CHAR or VARCHAR2.
- Change the precision of a numeric column.
- Change the data type of a column.
- Change the default value of a column.
6. 3. Alter Table 6. 3. 1. <A href="/Tutorial/Oracle/0120__Table/AlteringaTable.htm">Altering a Table</a> 6. 3. 2. Some of the aspects of a column you can modify using ALTER TABLE 6. 3. 3. <A href="/Tutorial/Oracle/0120__Table/AddingaColumn.htm">Adding a Column</a> 6. 3. 4. <A href="/Tutorial/Oracle/0120__Table/ADDinitiallycreatedDATEDEFAULTSYSDATENOTNULL.htm">ADD initially_created DATE DEFAULT SYSDATE NOT NULL;</a> 6. 3. 5. <A href="/Tutorial/Oracle/0120__Table/ChangingtheSizeofaColumn.htm">Changing the Size of a Column</a> 6. 3. 6. <A href="/Tutorial/Oracle/0120__Table/Decreasethelengthofacolumn.htm">Decrease the length of a column</a> 6. 3. 7. <A href="/Tutorial/Oracle/0120__Table/ChangingthePrecisionofaNumericColumn.htm">Changing the Precision of a Numeric Column</a> 6. 3. 8. <A href="/Tutorial/Oracle/0120__Table/Decreasetheprecisionofanumericcolumn.htm">Decrease the precision of a numeric column</a> 6. 3. 9. <A href="/Tutorial/Oracle/0120__Table/ChangingtheDataTypeofaColumn.htm">Changing the Data Type of a Column</a> 6. 3. 10. <A href="/Tutorial/Oracle/0120__Table/Filldataintonewaddedtablecolumn.htm">Fill data into new added table column</a> 6. 3. 11. <A href="/Tutorial/Oracle/0120__Table/ChangingtheDefaultValueofaColumn.htm">Changing the Default Value of a Column</a> 6. 3. 12. <A href="/Tutorial/Oracle/0120__Table/Altertabletoaddnewconstraintfornewaddedcolumn.htm">Alter table to add new constraint for new added column</a> 6. 3. 13. <A href="/Tutorial/Oracle/0120__Table/ALTERTABLEtoDISABLEaCONSTRAINT.htm">ALTER TABLE to DISABLE a CONSTRAINT</a> 6. 3. 14. <A href="/Tutorial/Oracle/0120__Table/Altertabletoaddprimarykey.htm">Alter table to add primary key</a> 6. 3. 15. <A href="/Tutorial/Oracle/0120__Table/Altertabletoaddprimarykeyacrossmorethanonecolumns.htm">Alter table to add primary key across more than one columns</a> 6. 3. 16. <A href="/Tutorial/Oracle/0120__Table/DroppingaColumn.htm">Dropping a Column</a> 6. 3. 17. <A href="/Tutorial/Oracle/0120__Table/Newaddedcolumnsareempty.htm">New added columns are empty</a> 6. 3. 18. <A href="/Tutorial/Oracle/0120__Table/Altertabletoadduniquewithtablespaceandstoragesetting.htm">Alter table to add unique with tablespace and storage setting</a> 6. 3. 19. <A href="/Tutorial/Oracle/0120__Table/Altertabletoaddprimarykeywithtablespaceandstoragesetting.htm">Alter table to add primary key with tablespace and storage setting</a> 6. 3. 20. <A href="/Tutorial/Oracle/0120__Table/altertablenologging.htm">alter table nologging</a>
