sqlserver中的if exists语句sqlserver中的if exists语句 在SQL Server中,IF EXISTS语句用于判断一个条件是否为真,并在条件成立时执行一段SQL代码。语法如下: ``` IF EXISTS (SELECT column_name FROM table_name WHERE condition) BEGIN --在条件为真时执行的代码 END ``` 其中,`SELECT column_name FROM table...
drop database [数据库名] if exists (select * from sys.databases where name = ’数据库名’) drop database [数据库名] 2 判断表是否存在 Sql代码 if exists (select * from sysobjects where id = object_id(N’[表名]’) and OBJECTPROPERTY(id, N’IsUserTable’) = 1) drop table [表名]...
IF EXISTS (<条件>) BEGIN -- 如果条件为真,执行这里的语句块 END ``` 在SQL Server 中,你可以在 SELECT、INSERT、UPDATE 和 DELETE 语句中使用 IF EXISTS 语句。以下是一些使用 IF EXISTS 语句的示例: - 在 SELECT 语句中使用 IF EXISTS: ```sql IF EXISTS (SELECT 1 FROM table_name WHERE column_...
columnNamestring✔️The name of the column to check if exists. defaultValuescalar✔️The value to use if the column doesn't exist. This value can be any scalar expression. For example, a reference to another column. Returns IfcolumnNameexists, then the column it refers to. Otherwisede...
SQL Puzzle: SQL Advance Query - Do the Multiplication for each GroupSQL Puzzle: SQL Advance Query - Do basic validation of Email Address Anvesh Patel Database Engineer December 10, 2018SQL ServerAnvesh Patel,Column Existence,Column Exists,database,database research and development,dbrnd,SQL Query...
alter table student drop column tel go ▓▓ 创建、删除表 --判断是否存在当前table if (exists (select * from sys.objects where name = 'classes')) -- EXISTS 是判断是否存在,和in类似,但效率要比in高 drop table classes go create table classes( ...
Sql代码 if object_id(’tempdb..#临时表名’) is not null drop table #临时表名 if object_id(’tempdb..#临时表名’) is not null drop table #临时表名 5 判断视图是否存在 Sql代码 --SQL Server 2000 IF EXISTS (SELECT * FROM sysviews WHERE object_id = ’[dbo].[视图名]’ ...
K）RF = 复制筛选存储过程 S = 系统表 TF = 表函数 TR = 触发器 U = ⽤户表 UQ = UNIQUE 约束（类型是 K）V = 视图 X = 扩展存储过程 */ 8 判断列是否存在 if exists(select * from syscolumns where id=object_id(’表名’) and name=’列名’)alter table 表名 drop column 列名 ...
--SQL Server 2005 IF EXISTS (SELECT * FROM sys.views WHERE object_id = ’[dbo].[视图名]’ 6 判断函数是否存在 Sql代码 -- 判断要创建的函数名是否存在 if exists (select * from dbo.sysobjects where id = object_id(N’[dbo].[函数名]’) and xtype in (N’FN’, N’IF’, N’TF’...
')SELECT'EXISTS'ELSESELECT'NOT EXISTS'***1.增加列:altertabletableNameaddcolumnNamevarchar(30)2.修改列类型:altertabletableNamealtercolumncolumnNamevarchar(4000)3.修改列的名称:EXECsp_rename'tableName.column1','column2'(把表名为tableName的column1列名修改为column2)4.删除列:altertabletableNamedropcol...