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this approach works if the user has permission to view the object. As a result, if the column length isNULL, we get the messageColumn does not exist. Otherwise, we seeColumn exists. We can also try changing the column name to check whether the ELSE statement works as intended. This meth...
if exists(select * from syscolumns where id=object_id('表名') and name='列名') alter table 表名 drop column 列名 9 判断列是否自增列 if columnproperty(object_id('table'),'col','IsIdentity')=1 print '自增列' else print '不是自增列' SELECT * FROM sys.columns WHERE object_id=OBJECT...
@level0name=N'dbo', @level1type=N'TABLE',@level1name=N'表名', @level2type=N'COLUMN',@level2name=N'列名'; go 示例: --如果表结构不存在时添加check约束 use testss; go --如果已存在表则删除 if exists(select * from sysobjects where name='test1' and xtype='U') drop table test1; ...
alter table 表名 drop column 列名 if exists(select * from syscolumns where id=object_id(’表名’) and name=’列名’) alter table 表名 drop column 列名 9 判断列是否自增列 Sql代码 if columnproperty(object_id(’table’),’col’,’IsIdentity’)=1 print ’自增列’ else print ’不是自增...
1 判断 数据库是否存在 Sql代码 if exists (select * from sys.databases where name = ’数据库名’) drop database [数据库名] if exists (select * from sys.databases where name = ’数据库名’) drop databa…
NOT IN：如果查询语句使用了NOT IN，内外表都可能进行全表扫描，可能不会使用索引。NOT EXISTS：即使使用NOT EXISTS，子查询仍然能利用表上的索引，因此通常比NOT IN更快。写法和用途：IN的where条件通常是... WHERE column IN 。EXISTS的where条件是... WHERE EXISTS 。两者都可以用来过滤数据，但在...
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]’ ...
Note:TheCHECKconstraint is used to validate data while insertion only. To check if the row exists or not, visitSQL EXISTS. Example 1: SQL CHECK Constraint Success -- apply the CHECK constraint to the amount columnCREATETABLEOrders (
Check for valid Ip address Check if amount is positive or negative Check If Column Is PRIMARY KEY Check if database exists? Check if Feb-29 is falling between start and end dates Check if file exists then delete it- fix code Check if installed SQL Server is an Eval copy Check if lo...