MySQL ANY ALL IN

mysql> select  4 >any(select 33  as V UNION ALL select 11) as R;

+---+

| R |

+---+

| 0 |

+---+

1 row in set (0.00 sec)

mysql> select  34 >any(select 33  as V UNION ALL select 11) as R;

+---+

| R |

+---+

| 1 |

+---+

1 row in set (0.01 sec)

-----------

ALL

mysql> select  34 >ALL(select 33  as V UNION ALL select 11) as R;

+---+

| R |

+---+

| 1 |

+---+

1 row in set (0.00 sec)

https://dev.mysql.com/doc/refman/8.4/en/any-in-some-subqueries.html

Syntax:

operand comparison_operator ANY (subquery)
operand IN (subquery)
operand comparison_operator SOME (subquery)

Where comparison_operator is one of these operators:

=  >  <  >=  <=  <>  !=

MySQL exists

 select  exists  (select  'A' where 5>10) as R;

+---+

| R |

+---+

| 0 |

+---+

Because     the evaluated query return   empty set, if return any value doesn't matter the value   it will return  1, doesn't matter if is null or 0.

select  'A' where 5>10;

Empty set (0.00 sec)

------------------------    exists   here will return 1

select  exists  (select  NULL) as R;

+------+

| R    |

+------+

|    1 |

+------+

1 row in set (0.00 sec)

-

 select  exists  (select  0) as R;

+---+

| R |

+---+

| 1 |

+---+

select 'Ambiorix' where exists(select 1);

+----------+

| Ambiorix |

+----------+

| Ambiorix |

+----------+

MySQL IF

mysql> select if(10>8,'A','B') as result;

+--------+

| result |

+--------+

| A      |

+--------+

--------------

mysql> select if(10>15,'A','B') as result;

+--------+

| result |

+--------+

| B      |

+--------+

MySQL case

mysql> set @i=4;

 mysql> select case @i

    -> when @i>3 then'A'

    -> else 'B'

    -> end as t;

------------

mysql> select case

    -> when 5>4 then  'A'

    -> when 5<6 then 'B'

    -> else 'C'

    -> end as t;

+---+