

IF NOT EXISTS(SELECT * FROM sys.columns 
            WHERE Name = N'isUnique' AND Object_ID = Object_ID(N'pal_SurfaceField'))
BEGIN
	ALTER TABLE dbo.pal_SurfaceField ADD
		isUnique bit NULL

	ALTER TABLE dbo.pal_SurfaceField ADD CONSTRAINT
		DF_pal_SurfaceField_isUnique DEFAULT 0 FOR isUnique

	ALTER TABLE dbo.pal_SurfaceField SET (LOCK_ESCALATION = TABLE)

END