How do I force the column alias to be of specific data type in MySQL?

For this, you can use CASE statement. Let us first create a table −

mysql> create table DemoTable1505    -> (    -> Value integer unsigned,    -> Status tinyint(1)    -> ); Query OK, 0 rows affected (0.47 sec)

Insert some records in the table using insert command −

mysql> insert into DemoTable1505 values(20,0); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable1505 values(45,1); Query OK, 1 row affected (0.08 sec)

Display all records from the table using select statement −

mysql> select * from DemoTable1505;

This will produce the following output −

+-------+--------+ | Value | Status | +-------+--------+ |    20 |      0 | |    45 |      1 | +-------+--------+ 2 rows in set (0.00 sec)

Here is the query to force the column alias to be of specific data type −

mysql> select case status    -> when 0 then cast(Value as signed)*1    -> when 1 then cast(Value as signed)*-1    -> end as AllValues from DemoTable1505;

This will produce the following output −

+-----------+ | AllValues | +-----------+ |        20 | |       -45 | +-----------+ 2 rows in set (0.00 sec)