Oracle PL/SQL/Char Functions/NVL
Содержание
- 1 Accommodate the datatype difference by placing a TO_CHAR function around the LAST_STOCK_DATE
- 2 Combine nvl and to_char
- 3 NVL() deals with date value
- 4 nvl( e2.ename, "NO BOSS! PARTY TIME!" )
- 5 NVL: Provide default value for NULL
- 6 NVL: Returns a substitute (some other value) if a value is null
- 7 NVL: Supply an NVL default that is of a different datatype
- 8 select nvl( "", "Yes """" is null" ) "Evaluate"
- 9 This will fail, because the datatypes of the two arguments are different
- 10 Use Nvl function in math calculation for null value
- 11 Use nvl in a function
- 12 Use NVL to check nullment in PL/SQL
- 13 Use NVL() to convert number columns and date columns
- 14 Use TRUNC function in NVL function
Accommodate the datatype difference by placing a TO_CHAR function around the LAST_STOCK_DATE
<source lang="sql">
SQL> SQL> CREATE TABLE product (
2 product_name VARCHAR2(25), 3 product_price NUMBER(4,2), 4 quantity_on_hand NUMBER(5,0), 5 last_stock_date DATE);
Table created. SQL> SQL> INSERT INTO product VALUES ("Small Widget", 99, 1, "15-JAN-03"); 1 row created. SQL> INSERT INTO product VALUES ("Medium Widget", 75, 1000, "15-JAN-02"); 1 row created. SQL> INSERT INTO product VALUES ("Product Number", 50, 100, "15-JAN-03"); 1 row created. SQL> INSERT INTO product VALUES ("Round Church Station", 25, 10000, null); 1 row created. SQL> SQL> SQL> SQL> SELECT product_name,
2 NVL(TO_CHAR(last_stock_date), "N/A") "Last Stocked" 3 FROM product;
PRODUCT_NAME Last Stoc
---------
Small Widget 15-JAN-03 Medium Widget 15-JAN-02 Product Number 15-JAN-03 Round Church Station N/A SQL> SQL> DROP TABLE product; Table dropped. SQL> SQL> SQL>
</source>
Combine nvl and to_char
<source lang="sql">
SQL> SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
2 ENAME VARCHAR2(10), 3 JOB VARCHAR2(9), 4 MGR NUMBER(4), 5 HIREDATE DATE, 6 SAL NUMBER(7, 2), 7 COMM NUMBER(7, 2), 8 DEPTNO NUMBER(2));
Table created. SQL> SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK", 7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7521, "WARD", "SALESMAN", 7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER", 7839, TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10); 1 row created. SQL> SQL> CREATE TABLE DEPT (DEPTNO NUMBER(2),DNAME VARCHAR2(14),LOC VARCHAR2(13) ); Table created. SQL> SQL> INSERT INTO DEPT VALUES (10, "ACCOUNTING", "NEW YORK"); 1 row created. SQL> INSERT INTO DEPT VALUES (20, "RESEARCH", "DALLAS"); 1 row created. SQL> INSERT INTO DEPT VALUES (30, "SALES", "CHICAGO"); 1 row created. SQL> INSERT INTO DEPT VALUES (40, "OPERATIONS", "BOSTON"); 1 row created. SQL> SQL> SQL> select nvl( to_char(mgr), "NULL" ) mgr
2 from emp 3 where ename = "KING";
MGR
NULL SQL> SQL> drop table emp cascade constraints; Table dropped. SQL> drop table dept cascade constraints; Table dropped. SQL>
</source>
NVL() deals with date value
<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> -- 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", NULL , 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 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> -- NVL(): convert a null to a known value. NVL(x, value) returns value if x is null; --otherwise, x is returned. SQL> SQL> SELECT id, NVL(start_date, to_date("20020101","YYYYMMDD")) FROM employee; ID NVL(START
---------
01 25-JUL-96 02 21-MAR-76 03 12-DEC-78 04 24-OCT-82 05 15-JAN-84 06 30-JUL-87 07 31-DEC-90 08 01-JAN-02 8 rows selected. SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL>
</source>
nvl( e2.ename, "NO BOSS! PARTY TIME!" )
<source lang="sql">
SQL> SQL> CREATE TABLE EMP
2 (EMPNO NUMBER(4) NOT NULL, 3 ENAME VARCHAR2(10), 4 JOB VARCHAR2(9), 5 MGR NUMBER(4), 6 HIREDATE DATE, 7 SAL NUMBER(7, 2), 8 COMM NUMBER(7, 2), 9 DEPTNO NUMBER(2) 10 );
Table created. SQL> SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK", 7902,TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698,TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7521, "WARD", "SALESMAN", 7698,TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER", 7839,TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10); 1 row created. SQL> SQL> SQL> select e.ename, nvl( e2.ename, "NO BOSS! PARTY TIME!" ) "MGR"
2 from emp e, emp e2 3 where e.mgr = e2.empno(+) 4 /
ENAME MGR
--------------------
FORD JONES SCOTT JONES JAMES BLAKE TURNER BLAKE MARTIN BLAKE WARD BLAKE ALLEN BLAKE MILLER CLARK ADAMS SCOTT CLARK KING BLAKE KING JONES KING SMITH FORD KING NO BOSS! PARTY TIME! 14 rows selected. SQL> SQL> drop table emp; Table dropped. SQL> --
</source>
NVL: Provide default value for NULL
<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> -- 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", NULL , 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 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> SELECT ID, NVL(Start_Date, to_Date("20000202","YYYYMMDD")) FROM Employee; ID NVL(START
---------
01 25-JUL-96 02 21-MAR-76 03 12-DEC-78 04 24-OCT-82 05 15-JAN-84 06 30-JUL-87 07 31-DEC-90 08 02-FEB-00 8 rows selected. SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL>
</source>
NVL: Returns a substitute (some other value) if a value is null
<source lang="sql">
SQL> SQL> -- create demo table SQL> create table TestTable(
2 ID VARCHAR2(4 BYTE) NOT NULL, 3 MyName VARCHAR2(10 BYTE), 4 MyDate DATE, 5 MyNumber Number(8,2) 6 ) 7 /
Table created. SQL> SQL> SQL> insert into TestTable (ID, MyName, MyDate, MyNumber) values("1","Alison",to_date("19960711","YYYYMMDD"),12.12); 1 row created. SQL> insert into TestTable (ID, MyName, MyDate, MyNumber) values("2","Jason",to_date("19970622","YYYYMMDD"),-12.12); 1 row created. SQL> insert into TestTable (ID, MyName, MyDate, MyNumber) values("3","Smith",to_date("19980513","YYYYMMDD"),22.1); 1 row created. SQL> insert into TestTable (ID, MyName, MyDate, MyNumber) values("4","Tailor",to_date("19990624","YYYYMMDD"),-2.12); 1 row created. SQL> insert into TestTable (ID, MyName, MyDate, MyNumber) values("5","Darlene",to_date("20000415","YYYYMMDD"),NULL); 1 row created. SQL> SQL> SQL> select * from TestTable; ID MYNAME MYDATE MYNUMBER
---------- --------- ----------
1 Alison 11-JUL-96 12.12 2 Jason 22-JUN-97 -12.12 3 Smith 13-MAY-98 22.1 4 Tailor 24-JUN-99 -2.12 5 Darlene 15-APR-00 SQL> SQL> -- NVL: Returns a substitute (some other value) if a value is null. SQL> SQL> SQL> SELECT MyNumber, NVL(MyNumber, 10) From TestTable;
MYNUMBER NVL(MYNUMBER,10)
----------------
12.12 12.12
-12.12 -12.12
22.1 22.1
-2.12 -2.12
10
SQL> SQL> SQL> SQL> SQL> SQL> drop table TestTable; Table dropped. SQL> SQL>
</source>
NVL: Supply an NVL default that is of a different datatype
<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", NULL, to_date("20020415","YYYYMMDD"), 1232.78,"Vancouver", NULL)
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 15-APR-02 1232.78 Vancouver 8 rows selected. SQL> SQL> --Supply an NVL default that is of a different datatype: SQL> SQL> SELECT ID, NVL(Description, "No Input") FROM Employee; ID NVL(DESCRIPTION
---------------
01 Programmer 02 Tester 03 Tester 04 Manager 05 Tester 06 Tester 07 Manager 08 No Input 8 rows selected. SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL>
</source>
select nvl( "", "Yes """" is null" ) "Evaluate"
<source lang="sql">
SQL> SQL> select nvl( "", "Yes """" is null" ) "Evaluate"
2 from dual 3 /
Evaluate
Yes "" is null 1 row selected. SQL> SQL> --
</source>
This will fail, because the datatypes of the two arguments are different
<source lang="sql">
SQL> SQL> CREATE TABLE product (
2 product_name VARCHAR2(25), 3 product_price NUMBER(4,2), 4 quantity_on_hand NUMBER(5,0), 5 last_stock_date DATE);
Table created. SQL> SQL> INSERT INTO product VALUES ("Small Widget", 99, 1, "15-JAN-03"); 1 row created. SQL> INSERT INTO product VALUES ("Medium Widget", 75, 1000, "15-JAN-02"); 1 row created. SQL> INSERT INTO product VALUES ("Product Number", 50, 100, "15-JAN-03"); 1 row created. SQL> INSERT INTO product VALUES ("Round Church Station", 25, 10000, null); 1 row created. SQL> SQL> SELECT product_name,
2 NVL(last_stock_date, "N/A") "Last Stocked"
3 FROM product;
NVL(last_stock_date, "N/A") "Last Stocked"
*
ERROR at line 2: ORA-01858: a non-numeric character was found where a numeric was expected
SQL> SQL> DROP TABLE product; Table dropped. SQL>
</source>
Use Nvl function in math calculation for null value
<source lang="sql">
SQL> SQL> CREATE TABLE emp (
2 emp_id NUMBER, 3 ename VARCHAR2(40), 4 hire_date DATE DEFAULT sysdate, 5 end_date DATE, 6 rate NUMBER(5,2), 7 CONSTRAINT emp_pk PRIMARY KEY (emp_id) 8 );
Table created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (101, "Mary", to_date("15-Nov-1961","dd-mon-yyyy"),null,169); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (102, "Tom", to_date("16-Sep-1964","dd-mon-yyyy"),to_date("5-May-2004","dd-mon-yyyy"),135); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (104, "Peter", to_date("29-Dec-1987","dd-mon-yyyy"),to_date("1-Apr-2004","dd-mon-yyyy"),99); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (105, "Mike", to_date("15-Jun-2004","dd-mon-yyyy"),null,121); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (107, "Less", to_date("2-Jan-2004","dd-mon-yyyy"),null,45); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (108, "Park", to_date("1-Mar-1994","dd-mon-yyyy"),to_date("15-Nov-2004","dd-mon-yyyy"),220); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (110, "Ink", to_date("4-Apr-2004","dd-mon-yyyy"),to_date("30-Sep-2004","dd-mon-yyyy"),84); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (111, "Tike", to_date("23-Aug-1976","dd-mon-yyyy"),null,100); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (112, "Inn", to_date("15-Nov-1961","dd-mon-yyyy"),to_date("4-Apr-2004","dd-mon-yyyy"),70); 1 row created. SQL> INSERT INTO emp(emp_id, ename, hire_date,end_date, rate)VALUES (113, "Kate", to_date("3-Mar-2004","dd-mon-yyyy"),to_date("31-Oct-2004","dd-mon-yyyy"),300); 1 row created. SQL> SQL> SQL> SET ECHO ON SQL> SELECT ename, NVL(rate,0) billing_rate,
2 NVL(rate,0) + 100 increased_rate 3 FROM emp 4 WHERE emp_id IN (113, 116);
Kate 300
400
1 row selected. SQL> SQL> SQL> SQL> drop table emp; Table dropped.
</source>
Use nvl in a function
<source lang="sql">
SQL> SQL> create or replace function total_compensation(
2 p_salary number, 3 p_commission number ) return number 4 deterministic as 5 begin 6 return nvl(p_salary,0) + nvl(p_commission,0); 7 end total_compensation; 8 /
Function created. SQL> SQL> select total_compensation(1,2) from dual; TOTAL_COMPENSATION(1,2)
3
SQL>
</source>
Use NVL to check nullment in PL/SQL
<source lang="sql">
SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
2 ENAME VARCHAR2(10), 3 JOB VARCHAR2(9), 4 MGR NUMBER(4), 5 HIREDATE DATE, 6 SAL NUMBER(7, 2), 7 COMM NUMBER(7, 2), 8 DEPTNO NUMBER(2));
Table created. SQL> SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK", 7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7521, "WARD", "SALESMAN", 7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER", 7839, TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10); 1 row created. SQL> SQL> DECLARE
2 lv_customer_name_txt emp.ename%TYPE;
3 lv_temp_txt VARCHAR2(10) NOT NULL DEFAULT "Testing";
4 lv_temp_txt2 lv_temp_txt%TYPE NOT NULL DEFAULT "Testing";
5 BEGIN
6 DBMS_OUTPUT.PUT_LINE("Customer Name: " || NVL(lv_customer_name_txt, "N/A"));
7 DBMS_OUTPUT.PUT_LINE("Temp Var: " || NVL(lv_temp_txt, "N/A"));
8 DBMS_OUTPUT.PUT_LINE("Temp Var2: " || NVL(lv_temp_txt2, "N/A"));
9 END;
10 /
Customer Name: N/A Temp Var: Testing Temp Var2: Testing PL/SQL procedure successfully completed. SQL> SQL> drop table emp; Table dropped.
</source>
Use NVL() to convert number columns and date columns
<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> -- 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 Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 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 Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester
8 rows selected. SQL> SQL> -- Use NVL() to convert number columns and date columns. SQL> SQL> SELECT id, first_name, last_name,
2 NVL(start_date, "01-JAN-2000") AS Start_Date FROM employee;
ID FIRST_NAME LAST_NAME START_DAT
---------- ---------- ---------
01 Jason Martin 25-JUL-96 02 Alison Mathews 21-MAR-76 03 James Smith 12-DEC-78 04 Celia Rice 24-OCT-82 05 Robert Black 15-JAN-84 06 Linda Green 30-JUL-87 07 David Larry 31-DEC-90 08 James Cat 17-SEP-96 8 rows selected. SQL> SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL>
</source>
Use TRUNC function in NVL function
<source lang="sql">
SQL> SQL> CREATE TABLE product (
2 product_name VARCHAR2(25), 3 product_price NUMBER(4,2), 4 quantity_on_hand NUMBER(5,0), 5 last_stock_date DATE);
Table created. SQL> SQL> INSERT INTO product VALUES ("Small Widget", 99, 1, "15-JAN-03"); 1 row created. SQL> INSERT INTO product VALUES ("Medium Widget", 75, 1000, "15-JAN-02"); 1 row created. SQL> INSERT INTO product VALUES ("Product Number", 50, 100, "15-JAN-03"); 1 row created. SQL> INSERT INTO product VALUES ("Round Church Station", 25, 10000, null); 1 row created. SQL> SQL> SQL> SELECT product_name,
2 NVL(last_stock_date, TRUNC(SYSDATE)) "Last Stocked" 3 FROM product;
PRODUCT_NAME Last Stoc
---------
Small Widget 15-JAN-03 Medium Widget 15-JAN-02 Product Number 15-JAN-03 Round Church Station 19-JUN-08 SQL> SQL> SQL> DROP TABLE product; Table dropped. SQL>
</source>
