MySQL inner join different results
- by Darryl at NetHosted
I am trying to work out why the following two queries return different results:
SELECT DISTINCT i.id, i.date
FROM `tblinvoices` i
INNER JOIN `tblinvoiceitems` it ON it.userid=i.userid
INNER JOIN `tblcustomfieldsvalues` cf ON it.relid=cf.relid
WHERE i.`tax` = 0
AND i.`date` BETWEEN '2012-07-01' AND '2012-09-31'
and
SELECT DISTINCT i.id, i.date
FROM `tblinvoices` i
WHERE i.`tax` = 0
AND i.`date` BETWEEN '2012-07-01' AND '2012-09-31'
Obviously the difference is the inner join here, but I don't understand why the one with the inner join is returning less results than the one without it, I would have thought since I didn't do any cross table references they should return the same results.
The final query I am working towards is
SELECT DISTINCT i.id, i.date
FROM `tblinvoices` i
INNER JOIN `tblinvoiceitems` it ON it.userid=i.userid
INNER JOIN `tblcustomfieldsvalues` cf ON it.relid=cf.relid
WHERE cf.`fieldid` =5
AND cf.`value`
REGEXP '[A-Za-z]'
AND i.`tax` = 0
AND i.`date` BETWEEN '2012-07-01' AND '2012-09-31'
But because of the different results that seem incorrect when I add the inner join (it removes some results that should be valid) it's not working at present, thanks.
