sql server 判断及增加列的默认值约束
IF NOT EXISTS ( SELECT name FROM sysobjects WHERE id = ( SELECT syscolumns.cdefault FROM sysobjects INNER JOIN syscolumns ON sysobjects.Id=syscolumns.Id WHERE sysobjects.name=N‘tableName‘ AND syscolumns.name=N‘columnName‘ ) ) BEGIN ALTER TABLE tableName add constraint DF_columnName DEFAULT N‘N‘ for columnName; PRINT N‘New add DF_columnName‘; END ELSE BEGIN PRINT N‘DEFAULT FOR columnName HAD EXISTS‘; END
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