MySQL IF function - WHERE 'field1 > 0' ? 'field2 < field1' : ''

Question

I need help translating this into a MySQL statement. I need to do something like:

WHERE IF 'field1 > 0' THEN 'field2 < field1'

Right now, I have this MySQL statement, but doesn't work?:

SELECT * FROM `my_table` WHERE IF(field1>0, field2<field1, 1=1) AND field3='1';

Please advise a solution for this. Thank you!

Answer 1

You only want to check field2 < field1 if field1 > 0 , so code it that way:

SELECT * FROM `my_table`
WHERE ((field1 > 0 AND field2 < field1) OR field1 <= 0)
AND field3 = '1';

Answer 2

You should be using a case statement:

SELECT * FROM `my_table` 
WHERE 
  field2< CASE WHEN (field1>0) THEN field1 ELSE field2+1 END 
  AND field3='1';

Answer 3

You can achieve this by using logical ANDs and ORs.

WHERE (field1 > 0 AND field2 < field1) OR (field1 <= 0 AND <else part of the statement>)

The <else part of the statement> is the condition that you want to check if field1 is not > 0 , unless there is no such a clause, in which case remove the OR and everything after it.