Question

我需要问一下,如何在选择住所中使用Alias,

我需要这样做。

SELECT (Complex SubQuery) AS A, (Another Sub Query WHERE ID = A) FROM TABLE

Answer 1

我们不能这样做:

SELECT (Complex SubQuery) AS A, (Another Sub Query WHERE ID = A) FROM TABLE

然而,你可以这样做:

SELECT (Another Sub Query WHERE ID = A.somecolumn)
FROM table
JOIN SELECT (Complex SubQuery) AS A on (A.X = TABLE.Y)

或

SELECT (Another Sub Query)
FROM table
WHERE table.afield IN (SELECT Complex SubQuery.otherfield)

The problem is that you cannot refer to aliases like this in the SELECT and WHERE clauses, because they will not have evaluated by the time the select or where part is executed.
You can also use a having clause, but having clauses do not use indexes and should be avoided if possible.

Answer 2

你可以像你这样重心。

SELECT Complex.A, (Another Sub Query WHERE ID = Complex.A)
FROM TABLE
CROSS JOIN ((Complex SubQuery) AS A) Complex

Answer 3

你们可以利用的另一个解决办法:

SELECT (Complex SubQuery) AS A, (Another Sub Query WHERE ID = A) 
FROM 
TABLE MAIN
OUTER APPLY (SELECT (Complex SubQuery) AS A)

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