IF EXISTS
   (SELECT OBJECT_NAME(OBJECT_ID) AS NameofConstraint, 
           SCHEMA_NAME(schema_id) AS SchemaName, 
           OBJECT_NAME(parent_object_id) AS TableName, 
           type_desc AS ConstraintType
    FROM sys.objects
    WHERE type_desc LIKE '%CONSTRAINT'
          AND OBJECT_NAME(OBJECT_ID) = 'DF_PDV_VD_TEF_NSU_SITEF')
    BEGIN
        ALTER TABLE PDV_VD_TEF DROP CONSTRAINT DF_PDV_VD_TEF_NSU_SITEF;
        ALTER TABLE PDV_VD_TEF ALTER COLUMN NSU_SITEF BIGINT NOT NULL;
END;
    ELSE
    ALTER TABLE PDV_VD_TEF ALTER COLUMN NSU_SITEF BIGINT NOT NULL;
	
