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Oracle Tutorials - What Is NULL in PL/SQL

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(Continued from previous topic...)

What Is NULL in PL/SQL?

NULL is a reserved key word and it stands for two things in PL/SQL:

  • NULL is an executable statement, and means doing nothing.
  • NULL is a data balue, and means no value.

The following sample script shows you examples of using NULL keyword:

DECLARE
  next_task CHAR(80);
BEGIN
  next_task := NULL; -- NULL value

  IF next_task IS NOT NULL THEN
     DBMS_OUTPUT.PUT_LINE('I am busy.');
  ELSE
     DBMS_OUTPUT.PUT_LINE('I am free.');
  END IF;
  
  IF next_task IS NULL THEN
     NULL; -- NULL statement
  ELSE
     DBMS_OUTPUT.PUT_LINE('... working on ' || next_task);
  END IF;
END;

This script should print this:

I am free.

(Continued on next topic...)

  1. Is PL/SQL Language Case Sensitive?
  2. How To Enter Comments in PL/SQL?
  3. What Are the Types of PL/SQL Code Blocks?
  4. What Is an Anonymous Block?
  5. What Is a Named Program Unit?
  6. What Is a Procedure?
  7. What Is a Function?
  8. How To Declare a Local Variable?
  9. How To Initialize Variables with Default Values?
  10. How To Assign Values to Variables?
  11. What Are the Arithmetic Operations?
  12. What Are the Numeric Comparison Operations?
  13. What Are the Logical Operations?
  14. How Many Categories of Data Types?
  15. How Many Scalar Data Types Are Supported in PL/SQL?
  16. How To Convert Character Types to Numeric Types?
  17. What Are the Execution Control Statements?
  18. How To Use "IF" Statements on Multiple Conditions?
  19. How To Use "WHILE" Loop Statements?
  20. How To Use "FOR" Loop Statements?
  21. What Is NULL in PL/SQL?
  22. How To Test NULL Values?

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