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;]