Sql Server系列:Update语句
UPDATE语句用来更新已有的数据,UPDATE语法:
[ WITH <common_table_expression> [...n] ] UPDATE [ TOP ( expression ) [ PERCENT ] ] { { table_alias | <object> | rowset_function_limited [ WITH ( <Table_Hint_Limited> [ ...n ] ) ] } | @table_variable } SET { column_name = { expression | DEFAULT | NULL } | { udt_column_name.{ { property_name = expression | field_name = expression } | method_name ( argument [ ,...n ] ) } } | column_name { .WRITE ( expression , @Offset , @Length ) } | @variable = expression | @variable = column = expression | column_name { += | -= | *= | /= | %= | &= | ^= | |= } expression | @variable { += | -= | *= | /= | %= | &= | ^= | |= } expression | @variable = column { += | -= | *= | /= | %= | &= | ^= | |= } expression } [ ,...n ] [ <OUTPUT Clause> ] [ FROM{ <table_source> } [ ,...n ] ] [ WHERE { <search_condition> | { [ CURRENT OF { { [ GLOBAL ] cursor_name } | cursor_variable_name } ] } } ] [ OPTION ( <query_hint> [ ,...n ] ) ] [ ; ] <object> ::= { [ server_name . database_name . schema_name . | database_name .[ schema_name ] . | schema_name . ] table_or_view_name}
1. 更新整列
UPDATE [dbo].[Product] SET [CreateDate] = GETDATE()
2. 指定计算值
UPDATE [dbo].[Product] SET [UnitPrice] = [UnitPrice] * 2
3. 使用DEFAULT值更新
将列CreateDate的默认值设置为GETDATE(),若未设置则默认值为空。
UPDATE [dbo].[Product] SET [CreateDate] = DEFAULT
4. WHERE条件限制更新多列字段
UPDATE [dbo].[Product] SET [ProductName] = ‘LINQ to SQL‘, [UnitPrice] = 100, [CreateDate] = GETDATE() WHERE [ProductID] = 1
5. 参考资料
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