Question

I have a table with different dates and one of them is separated in 3 fields:
PassDay, PassMonth, PassYear.

I want to compare these dates with an other datetime orig_date so what I did is

select `orig_date`, CONCAT_WS('-',`PassYear`,`PassMonth`,`PassDay`) as `pass_expiration` where `pass_expiration` < `orig_date`;

The problem is that the month is stored as a month name (January) and not a number (01), so my result for pass_expiration is 2013-April-15 for example.

Is there a way to transform this (2013-April-15) to a regular datetime directly from the query?

Answer 1

You want str_to_date:

where STR_TO_DATE(CONCAT_WS('-',PassYear,PassMonth,PassDay),'%Y-%M-%d') < orig_date

Also, as a note, you can’t reference a computed column in the where clause. Only in the order by clause (where is a predicate that’s used to filter results from the table; order by is run after the column set is calc’d).