Mysql内连接两个表

Question

I have two tables carry and transactions, and want to select member records from transaction table where purpose=5 based on the same member id in carry table with left_carry or right carry != 0.

I tried with the sql bellow but getting duplicate and multiple purpose data from transaction table. the result is as in the link: http://prntscr.com/9tles2

My code is:

select distinct c.member_id,c.left_carry,c.middle_carry, t.purpose 
from carry c
inner join transactions t on t.member_id = c.member_id
where c.left_carry != 0 or c.middle_carry != 0 and t.purpose = 1

Answer 1

Mixing OR and AND can be a little confusing. It is best to add some brackets to make it clear what is intended.

This should clear up your problem

select distinct c.member_id,c.left_carry,c.middle_carry, t.purpose 
from carry c
  inner join transactions t on t.member_id = c.member_id
where (   c.left_carry != 0 
       or c.middle_carry != 0) 
  and t.purpose = 1