--主键表
SELECT TOP 50 *
FROM sys.key_constraints

--没有主键的表
SELECT TOP 50 *
FROM sys.tables a
WHERE a.object_id NOT IN(
	SELECT parent_object_id
	FROM sys.key_constraints
)

	SELECT TOP 50 *
	FROM sys.parameters 

--查询计算列
SELECT TOP 50 *
FROM sys.computed_columns