solve Problems with Correlated subqueries
SELECT A.SHIP_CABIN_ID, A.ROOM_STYLE, A.ROOM_NUMBER, A.SQ_FT
FROM SHIP_CABINS A
WHERE A.SQ_FT >
(SELECT AVG(SQ_FT) FROM SHIP_CABINS WHERE ROOM_STYLE. = A.ROOM_STYLE)
ORDER BY A.ROOM_NUMBER;
Correlated subqueries can exist in SELECT, UPDATE, and DELETE statements.
They are “correlated” by way of a column reference from the parent query within the
subquery.
A table alias is not necessarily required in the subquery if no column name
conflict exists.
conflict exists.
Its important to note that correlated subqueries may introduce performance
degradation into a query.
degradation into a query.
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/22327710/viewspace-762784/ ，如需转载，请注明出处，否则将追究法律责任。
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