PRINT N'Dropping unnamed constraints on [dbo].[Animals]...';
DECLARE @TableName AS NVARCHAR(255)
DECLARE @ColumnName AS NVARCHAR(255)
DECLARE @ConstraintName AS NVARCHAR(255)
DECLARE @DropConstraintSQL AS NVARCHAR(255)
SET @TableName = 'Animals'
SET @ColumnName = 'NumberOfLegs'
--Get the name of the constraint that will be dropped
SET @ConstraintName =
(SELECT TOP 1 o.name FROM sysobjects o
JOIN syscolumns c
ON o.id = c.cdefault
JOIN sysobjects t
ON c.id = t.id
WHERE o.xtype = 'd'
AND c.name = @ColumnName
AND t.name = @TableName)
SELECT @ConstraintName
--Build a query string that will drop the constraint
SET @DropConstraintSQL = 'ALTER TABLE dbo.' + @TableName + ' DROP ' + @ConstraintName
--Execute the sql to drop the constraint
EXEC (@DropConstraintSQL)