Oracle PL/SQL/Conversion Functions/NULLIF
NULLIF() compares two expressions. If they are equal, it returns NULL. Otherwise, it returns the first expression.
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SQL> Syntax: NULLIF( <expression1>,<expression2>) SQL> SQL> SELECT
2 NULLIF("ABC","ABC") equal, 3 NULLIF ("ABC","DEF") diff from dual;
EQU DIF --- ---
ABC </source>
select nullif( 1, 1 )
<source lang="sql">
SQL> SQL> select nullif( 1, 1 )
2 from dual;
NULLIF(1,1)
1 row selected. SQL> SQL> --
</source>
select nullif( 1, null )
<source lang="sql">
SQL> SQL> select nullif( 1, null )
2 from dual;
NULLIF(1,NULL)
1
1 row selected. SQL> SQL> SQL> --
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