ms sql 之 内联列别名／外联列别名

/*生成测试数据*/

DECLARE @tb TABLE (ids INT)

INSERT INTO @tb

SELECT 1 UNION

SELECT 2 UNION 

SELECT 3 UNION

SELECT 4

 

内联列别名：

SELECT ids,COUNT(tt) FROM (SELECT COUNT(1) +1 AS 'ids' , 'temp' AS 'tt' FROM @tb ) tbs GROUP BY ids

外联列别名：

SELECT ids,COUNT(tt) FROM (SELECT COUNT(1) +1 AS 'ids' , 'temp' AS 'tt' FROM @tb ) AS tbs (ids,tt) GROUP BY ids