1、判断表是否存在

select * from sysobjects where id = object_id(表名) and OBJECTPROPERTY(id, N'IsUserTable') = 1

2、判断视图是否存在

select table_name from information_schema.views where table_name = 视图名

或者

SELECT * FROM dbo.sysobjects WHERE id = object_id('视图名') AND OBJECTPROPERTY(id, N'IsView') = 1

3、判断函数是否存在

select * from sysobjects where xtype='fn' and name='函数名'

或者

select * from dbo.sysobjects where id = object_id(N'[dbo].[函数名]') and xtype in (N'FN', N'IF', N'TF')

4、判断字段是否存在

select 1 from syscolumns where id=object_id('表名') and name='字段名'

5、判断索引是否存在

1. if not exists(select * from sysindexes where id=object_id('表名') and name='索引名')

2. create nonclustered index [索引名] on [表名](字段 asc,字段 asc)

3. go

6、判断存储过程是否存在

1. IF exists(SELECT * FROM sysobjects WHERE id=object_id(N'[master].[存储过程名称]') and xtype='P')

2. begin

3. drop procedure [master].[存储过程名称]

4. End

5. GO

   -- SQL SERVER 判断是否存在某个触发器、储存过程

   -- 判断储存过程,如果存在则删除
   IF (EXISTS(SELECT * FROM sysobjects WHERE name='procedurename' AND type='P'))
   DROP PROCEDURE procedurename

   -- 判断触发器,如果存在则删除
   IF (EXISTS(SELECT * FROM sysobjects WHERE id=object_id(N'[dbo].[triggername]') AND OBJECTPROPERTY(id, N'IsTrigger') = 1))
   DROP TRIGGER triggername

   -- 判断用户函数是否存在,如果存在则删除
   -- 此处type有两种: 'TF'- Table-Value Function 表值函数 'FN'- Scalar-Value Function 标量值函数
   IF (EXISTS(SELECT * FROM sysobjects WHERE id=object_id(N'[dbo].[userfunction]') AND (type='FN' OR type='TF')))
   DROP FUNCTION userfunction
   
   -- 判断视图是否存在,存在则删除
   IF (EXISTS(SELECT TABLE_NAME FROM INFORMATION_SCHEMA.VIEWS WHERE TABLE_NAME=N'viewname'))
   DROP VIEW viewname
   
   -- 判断用户表 是否存在,若存在则删除
   IF (EXISTS(SELECT * FROM sysobjects WHERE id=N'tablename' AND OBJECTPROPERTY(id, N'IsUserTable')=1))
   DROP TABLE tablename

   -- 判断数据库,如果存在则删除
   IF (EXISTS(SELECT * FROM master.dbo.sysdatabases WHERE dbid=db_ID('dbname')))
   DROP DATABASE dbname

   
   -- 如果提示：删除数据库时提示数据库正在被使用，无法删除(Cannot drop database databasename because it is currently in use)，使用：

   IF (EXISTS(SELECT * FROM master.dbo.sysdatabases WHERE dbid=db_ID('dbname')))

   BEGIN

   　　USE master
   　　ALTER DATABASE dbname
   　　SET single_user
   　　WITH ROLLBACK IMMEDIATE
   　　DROP DATABASE dbname

   END