| 23. 5. 1. IS NULL |
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The IS NULL operator is used to test a NULL value. |
Variables you declare in a PL/SQL block are also initially null, or have no value. |
Variables remain null until your code specifically assigns a value to them. |
The Syntax for IS NULL: |
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the_value is a variable, or another expression. |
If the value is null, then the IS NULL operator returns true. |
You can also reverse the test by using IS NOT NULL. |
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SQL>
SQL> --Remember to execute: SET SERVEROUTPUT ON
SQL> DECLARE
2 test INTEGER;
3 BEGIN
4 IF test IS NULL THEN
5 DBMS_OUTPUT.PUT_LINE('The variable TEST is null.');
6 END IF;
7 test := 1;
8 DBMS_OUTPUT.PUT_LINE('TEST = ' || TO_CHAR(test));
9 IF test IS NOT NULL THEN
10 DBMS_OUTPUT.PUT_LINE('The variable TEST is NOT null.');
11 END IF;
12 END;
13 /
The variable TEST is null.
TEST = 1
The variable TEST is NOT null.
PL/SQL procedure successfully completed.
SQL>
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