Question

I have added a new column that should store a timestamp value. This value currently exists in another table. So I tried to build a query to update my new column using the other table.

This is my current query:

    UPDATE `gc_users` U 
    SET    `registration_date` = ( SELECT `joindate` 
                                   FROM    `vb_user` 
                                   WHERE   `username` = U.`name` 
                                   LIMIT 0,1
                                 )

The problem is that after updating registration_date the value is 0000-00-00 00:00:00

New table: gc_users

• Column: registration_date ( timestamp )
• Example: 2013-01-11 15:24:04

Source table: va_user

• Column: joindate ( int )
• Example: 1354290120

Answer 1

use FROM_UNIXTIME

UPDATE  `gc_users` U
         INNER JOIN `vb_user` a
            ON a.`username` = U.`name`
SET     u.`registration_date` = FROM_UNIXTIME(a.`joindate`)
LIMIT   0,1

• FROM_UNIXTIME