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如何使用亞音速形成此查詢?亞音速嵌套查詢
SELECT A.categoryname,
(SELECT COUNT(*)
FROM items B
WHERE a.categoryid = b.categoryid) AS TOT
FROM category A
如何使用亞音速形成此查詢?亞音速嵌套查詢
SELECT A.categoryname,
(SELECT COUNT(*)
FROM items B
WHERE a.categoryid = b.categoryid) AS TOT
FROM category A
你可以重寫查詢是這樣的:
SELECT A.categoryname, COUNT(B.categoryid) AS TOT
FROM category A LEFT OUTER JOIN items B ON A.categoryid = B.categoryid
GROUP BY A.id, A.categoryname
如果沒有類別具有相同的名稱,則可以省略A.id
列。
然後用亞音速類似這樣(的確切語法可能會有所不同...):
DAL.DB.Select(
Aggregate.GroupBy(DAL.A.categorynameColumn),
Aggregate.GroupBy(DAL.A.idColumn)
Aggregate.Count(DAL.B.categoryidColumn, "Tot")
)
.From<DAL.A>().LeftOuterJoin(DAL.B.categoryidColumn, DAL.A.categoryidColumn)