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Oracle Tutorials - Test NULL Values
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How To Test NULL Values?
There ate two special comparison operators you can use on NULL values:
- "variable IS NULL" - Returns TRUE if the variable value is NULL.
- "variable IS NOT NULL" - Return TRUE if the variable value is not NULL.
The following sample script shows you examples of comparing NULL values:
next_task := NULL;
IF next_task IS NOT NULL THEN
DBMS_OUTPUT.PUT_LINE('I am busy.');
DBMS_OUTPUT.PUT_LINE('I am free.');
IF next_task IS NULL THEN
DBMS_OUTPUT.PUT_LINE('... working on ' || next_task);
Note that "variable = NULL" is not a valid operation. This script should print this:
I am free.
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