[英]How to implement this query in MySQL?
我的查詢與此非常相似。
(SELECT emailid FROM usereducation WHERE presfuncarea = '$funcarea')
intersect
(SELECT emailid FROM userprofession WHERE totexpyear >= '$minexp')
由於MySQL不支持相交,因此我必須找到正確的解決方案。
這應該做的工作:
SELECT p.emailid
FROM usereducation e JOIN userprofession p ON p.emailid = e.emailid
WHERE e.presfuncarea = '$funcarea'
AND p.totexpyear >= '$minexp'
MySQL支持EXISTS。 這應該工作:
SELECT UE.emailid
FROM usereducation AS UE
WHERE UE.presfuncarea = '$funcarea'
AND NOT EXISTS
(
SELECT * FROM userprofession AS UP
WHERE UE.emailid = UP.emailID AND UP.totexpyear >= '$minexp'
)
來自: http : //www.bitbybit.dk/carsten/blog/?p=71
INTERSECT只是內部聯接,我們在其中將一個表的元組與另一個表的元組進行比較,並在清除重復項時選擇兩個表中的元組。 所以
SELECT member_id, name FROM a
INTERSECT
SELECT member_id, name FROM b
可以簡單地重寫為
SELECT a.member_id, a.name
FROM a INNER JOIN b
USING (member_id, name)
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