[英]MySQL SELECT query on junction table with multiple tables
我有四个表,假设每个表只有一个ID作为列。
listings
feature
location
l_f_location
作为带有FK的联结表,在listingId
, featureId
, locationId
我尝试在l_f_location
表中查询给定的locationIds
集(逻辑AND匹配),结果只希望那些与所有locationIds
匹配的列表,例如(7 AND 9 AND 10)。
l_f_location
看起来像
listingId featureId locationId
10 5 7
10 7 7
10 8 9
11 4 7
11 8 9
11 9 10
11 12 14
在这种情况下,目标是仅检索listingId
11-与locationIds
7、9和10的集合匹配。
我尝试了以下查询
“ SELECT id, COUNT(*) as num FROM l_f_locations WHERE locationId IN ( 7, 9, 10) GROUP by listingId, locationId HAVING num = 3
”
但是,随着分组的开始,计数值会错误。
类似的查询可以在更简单的联结表上完美地工作,例如仅l_location,例如“ SELECT id, COUNT(*) as num FROM l_location WHERE locationId IN ( 7, 9, 10) GROUP by listingId HAVING num = 3
”。
Rgds,P。
我假设相同的listingId
和locationId
可以具有多个featureId
? 否则,它会容易得多。
如果是这样的话:
SELECT listingId, COUNT(*) as num
FROM
(SELECT DISTINCT listingId, locationId
FROM l_f_locations
WHERE locationId IN ( 7, 9, 10)) AS sub
GROUP by listingId, HAVING num = 3
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