SELECT doesn't return value on "AND"
Am I missing something? My table contains:
country
with the value 'usa
'school-type
with the value '4 Year University
'
If I use row 2, the query returns '220'. If I use row 4, it also returns '220'. If I use both with 'OR' between the开发者_如何学JAVAm, it returns '220' twice, but if I use 'AND', it doesn't return anything. Any ideas?
SELECT post_id FROM wp_postmeta WHERE
( (meta_key='school-type' AND meta_value='Community College')
OR (meta_key='school-type' AND meta_value='4 Year University'))
AND
( (meta_key='country' AND meta_value='usa')
OR (meta_key='country' AND meta_value='canada'))
The problem is, a single row can't have a meta_key
of both "school-type" and "country". Combining the two different searches results in 0 results because of this.
WHERE
filters each row, so it is not possible for meta_key
to be school-type and country.
Try a HAVING
clause:
SELECT post_id
FROM wp_postmeta
WHERE meta_key='school-type' OR meta_key='country'
GROUP BY post_id
HAVING SUM(
IF(meta_key='school-type',
meta_value='Community College' OR meta_value='4 Year University',
meta_value='usa' OR meta_value='canada'
)) = 2
Or, If you want to get both rows:
SELECT post_id
FROM wp_postmeta
WHERE
((meta_key='school-type' AND meta_value='Community College') OR (meta_key='school-type' AND meta_value='4 Year University'))
OR
((meta_key='country' AND meta_value='usa') OR (meta_key='country' AND meta_value='canada'))
you query is wrong . Let's take example if meta_key='school-type' than it can't be country so your second condition will always return fast.
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