select

从数据库中检索行，并允许从一个或多个表中选择一个或多个行或列。虽然 select 语句的完整语法较复杂，但是其主要的子句可归纳如下：

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 ] ]

可以在查询之间使用 union 运算符，以将查询的结果组合成单个结果集。

语法

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>]