在sql server上运行条件DDL语句

IF NOT EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[MyTable]') AND type in (N'U'))
BEGIN
    CREATE TABLE [dbo].[MyTable](
        [Id] [int] IDENTITY(1,1) NOT NULL,
        [Name] [nvarchar](50) NOT NULL,
        [Age] [int] NOT NULL,
     CONSTRAINT [PK_MyTable] PRIMARY KEY CLUSTERED 
    (
        [Id] ASC
    )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
    ) ON [PRIMARY]
END

IF EXISTS (SELECT * FROM sys.columns WHERE object_id = OBJECT_ID(N'[dbo].[MyTable]') AND name = 'Email')
BEGIN
    ALTER TABLE [dbo].[MyTable] DROP COLUMN [Email]
END

IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[MyTable]') AND type in (N'U'))
BEGIN
    DROP TABLE [dbo].[MyTable]
END