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從數(shù)據(jù)庫(kù)中檢索行，并允許從一個(gè)或多個(gè)表中選擇一個(gè)或多個(gè)行或列。雖然 SELECT 語(yǔ)句的完整語(yǔ)法較復(fù)雜，但是其主要的子句可歸納如下：

SELECT select_list

[ INTO new_table ]

FROM table_source

[ WHERE search_condition ]

[ GROUP BY group_by_expression ]

[ HAVING search_condition ]

[ ORDER BY order_expression [ ASC | DESC ] ]

可以在查詢(xún)之間使用 UNION 運(yùn)算符，以將查詢(xún)的結(jié)果組合成單個(gè)結(jié)果集。

語(yǔ)法

SELECT statement ::=

    < query_expression >

    [ ORDER BY { order_by_expression | column_position [ ASC | DESC ] }

        [ ,...n ]    ]

    [ COMPUTE

        { { AVG | COUNT | MAX | MIN | SUM } ( expression ) } [ ,...n ]

        [ BY expression [ ,...n ] ]

    ]

    [ FOR { BROWSE | XML { RAW | AUTO | EXPLICIT }

            [ , XMLDATA ]

            [ , ELEMENTS ]

            [ , BINARY base64 ]

        }

]

    [ OPTION ( < query_hint > [ ,...n ]) ]

< query expression > ::=

    { < query specification > | ( < query expression > ) }

    [ UNION [ ALL ] < query specification | ( < query expression > ) [...n ] ]

< query specification > ::=

    SELECT [ ALL | DISTINCT ]

        [ { TOP integer | TOP integer PERCENT } [ WITH TIES ] ]

        < select_list >

    [ INTO new_table ]

    [ FROM { < table_source > } [ ,...n ] ]

    [ WHERE < search_condition > ]

    [ GROUP BY [ ALL ] group_by_expression [ ,...n ]

        [ WITH { CUBE | ROLLUP } ]

    ]

    [HAVING <search_condition>]

由于 SELECT 語(yǔ)句的復(fù)雜性，下面按子句說(shuō)明詳細(xì)的語(yǔ)法元素和參數(shù)：

SELECT 子句

INTO 子句

FROM 子句

WHERE 子句

GROUP BY 子句

HAVING 子句

UNION 運(yùn)算符

ORDER BY 子句

COMPUTE 子句

FOR 子句

OPTION 子句