Demonstrates that empty strings are NULL : VARCHAR2 « PL SQL Data Types « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. PL SQL Data Types
3. VARCHAR2

SQL> DECLARE
  2     empty_varchar2 VARCHAR2(10) := '';
  3     empty_char CHAR(10) := '';
  4  BEGIN
  5     IF empty_varchar2 IS NULL THEN
  6        DBMS_OUTPUT.PUT_LINE('empty_varchar2 is NULL');
  7     END IF;
  8
  9     IF '' IS NULL THEN
 10        DBMS_OUTPUT.PUT_LINE(''''' is NULL');
 11     END IF;
 12
 13     IF empty_char IS NULL THEN
 14        DBMS_OUTPUT.PUT_LINE('empty_char is NULL');
 15     END IF;
 16  END;
 17  /

PL/SQL procedure successfully completed.

SQL>
SQL>