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[Teach Youself SQL in 十 Minutes] S

发布时间: 2012-07-19 16:02:19 作者: rapoo

[Teach Youself SQL in 10 Minutes] SELECT Clause Ordering

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Clause

Description

Required

SELECT

Columns or expressions to be returned

Yes

FROM

Table to retrieve data from

Only if selecting data from a table

WHERE

Row-level filtering

No

GROUP BY

Group specification

Only if calculating aggregates by group

HAVING

Group-level filtering

No

ORDER BY

Output sort order

No

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