（二）判断表或其他对象及列是否存在

--判断某个表或对象是否存在
IF(EXISTS (SELECT * FROM sys.objects WHERE name ='R'))
   PRINT '存在';
GO
IF(EXISTS (SELECT * FROM sys.objects WHERE object_id=object_id('testHome')))
   PRINT '存在';
GO
IF(object_id('testHome','U')IS NOT NULL)
   PRINT '存在';
GO

--判断该列名是否存在，如果存在就删除
IF(EXISTS (SELECT * FROM sys.columns WHERE object_id=OBJECT_ID('R') and name='Que'))
   ALTER TABLE R DROP COLUMN Que 
GO 
IF(EXISTS (SELECT * FROM INFORMATION_SCHEMA.columns WHERE table_name='R' and column_name='snamea'))
   ALTER TABLE R DROP COLUMN snamea 
GO