SQL_SERVER培训.doc

SQL SERVER培训 如何使用Select、Insert、Delete和Update。 (1)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] 由于 SELECT 语句的复杂性，下面按子句说明详细的语法元素和参数： SELECT 子句INTO 子句FROM 子句WHERE 子句GROUP BY 子句HAVING 子句UNION 运算符ORDER BY 子句COMPUTE 子句FOR 子句OPTION 子句 SELECT 子句 指定由查询返回的列。 语法 SELECT [ ALL | DISTINCT ]????[ TOP n [ PERCENT ] [ WITH TIES ] ]???? select_list select_list ::= ????{????* ????????| { table_name | view_name | table_alias }.*????????| ????{ column_name | expression | IDENTITYCOL | ROWGUIDCOL }????????????[ [ AS ] column_alias ]????????| column_alias = expression????}????[ ,...n ] 参数 ALL 指定在结果集中可以显示重复行。ALL 是默认设置。 DISTINCT 指定在结果集中只能显示唯一行。为了 DISTINCT 关键字的用途，空值被认为相等。 TOP n [PERCENT] 指定只从查询结果集中输出前 n 行。n 是介于 0 和 4294967295 之间的整数。如果还指定了 PERCENT，则只从结果集中输