if (not exists (select name from syscolumns where id = object_id('Pub_Domain') and name = 'UploadFileSize'))   
    Begin

    ALTER TABLE Pub_Domain ADD
    UploadFileSize int default(4000)

    EXEC sys.sp_addextendedproperty @name=N'MS_Description', @value=N'上传文件大小
   type:text
   regex:num1
   regex_msg:最大上传大小应为数字
   tooltip:平台允许上传的最大文件大小(MB)' ,@level0type=N'SCHEMA', @level0name=N'dbo', @level1type=N'TABLE', @level1name=N'Pub_Domain', @level2type=N'COLUMN', @level2name=N'UploadFileSize'

    End