IS NULL operator checks whether a variable value is null : IS NULL « Collections « Oracle PL/SQL Tutorial

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3. IS NULL

SQL>
SQL>  DECLARE
  2     var BOOLEAN;
  3    BEGIN
  4     IF var IS NULL THEN
  5      dbms_output.put_line('It is null.');
  6     END IF;
  7    END;
  8    /
It is null.

PL/SQL procedure successfully completed.

SQL>
SQL>
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