Oracle PL/SQL Tutorial/Query Select/DISTINCT — различия между версиями
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Текущая версия на 10:09, 26 мая 2010
Displaying Distinct Rows
You can suppress the display of duplicate rows using the DISTINCT keyword.
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> SELECT Description FROM employee
2 /
DESCRIPTION
---------------
Programmer
Tester
Tester
Manager
Tester
Tester
Manager
Tester
8 rows selected.
SQL> SELECT DISTINCT Description FROM employee
2 /
DESCRIPTION
---------------
Programmer
Manager
Tester
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
SQL>
Select distinct column and other columns
SQL>
SQL>
SQL> CREATE TABLE employees (
2 au_id CHAR(3) NOT NULL,
3 au_fname VARCHAR(15) NOT NULL,
4 au_lname VARCHAR(15) NOT NULL,
5 phone VARCHAR(12) NULL ,
6 address VARCHAR(20) NULL ,
7 city VARCHAR(15) NULL ,
8 state CHAR(2) NULL ,
9 zip CHAR(5) NULL
10 );
Table created.
SQL>
SQL> INSERT INTO employees VALUES("A01","S","B","111-111-1111","75 St","Boston","NY","11111");
1 row created.
SQL> INSERT INTO employees VALUES("A02","W","H","222-222-2222","2922 Rd","Boston","CO","22222");
1 row created.
SQL> INSERT INTO employees VALUES("A03","H","H","333-333-3333","3800 Ave, #14F","San Francisco","CA","33333");
1 row created.
SQL> INSERT INTO employees VALUES("A04","K","H","444-444-4444","3800 Ave, #14F","San Francisco","CA","44444");
1 row created.
SQL> INSERT INTO employees VALUES("A05","C","K","555-555-5555","114 St","New York","NY","55555");
1 row created.
SQL> INSERT INTO employees VALUES("A06"," ","K","666-666-666","390 Mall","Palo Alto","CA","66666");
1 row created.
SQL> INSERT INTO employees VALUES("A07","P","O","777-777-7777","1442 St","Sarasota","FL","77777");
1 row created.
SQL>
SQL>
SQL> SELECT DISTINCT city, state
2 FROM employees;
CITY ST
--------------- --
San Francisco CA
Palo Alto CA
Sarasota FL
New York NY
Boston NY
Boston CO
6 rows selected.
SQL>
SQL>
SQL> drop table employees;
Table dropped.
Select distinct value
SQL>
SQL> CREATE TABLE employees (
2 au_id CHAR(3) NOT NULL,
3 au_fname VARCHAR(15) NOT NULL,
4 au_lname VARCHAR(15) NOT NULL,
5 phone VARCHAR(12) NULL ,
6 address VARCHAR(20) NULL ,
7 city VARCHAR(15) NULL ,
8 state CHAR(2) NULL ,
9 zip CHAR(5) NULL
10 );
Table created.
SQL>
SQL> INSERT INTO employees VALUES("A01","S","B","111-111-1111","75 St","Boston","NY","11111");
1 row created.
SQL> INSERT INTO employees VALUES("A02","W","H","222-222-2222","2922 Rd","Boston","CO","22222");
1 row created.
SQL> INSERT INTO employees VALUES("A03","H","H","333-333-3333","3800 Ave, #14F","San Francisco","CA","33333");
1 row created.
SQL> INSERT INTO employees VALUES("A04","K","H","444-444-4444","3800 Ave, #14F","San Francisco","CA","44444");
1 row created.
SQL> INSERT INTO employees VALUES("A05","C","K","555-555-5555","114 St","New York","NY","55555");
1 row created.
SQL> INSERT INTO employees VALUES("A06"," ","K","666-666-666","390 Mall","Palo Alto","CA","66666");
1 row created.
SQL> INSERT INTO employees VALUES("A07","P","O","777-777-7777","1442 St","Sarasota","FL","77777");
1 row created.
SQL>
SQL>
SQL> SELECT DISTINCT state
2 FROM employees;
ST
--
CA
NY
CO
FL
SQL>
SQL>
SQL> drop table employees;
Table dropped.