Question

目前我从2个表中选择了这个：

(SELECT e.id, e.num, '1' as TBL
FROM events e
)

UNION ALL

(SELECT p.id, p.num, '2' as TBL
FROM places p
)

ORDER BY 2 DESC

它返回num排序的值，如下所示：

id  |  num  |  TBL
 3  |    9  |    2
 1  |    8  |    2
 4  |    7  |    1
 1  |    4  |    1
 7  |    1  |    2

但我的目标是在选择中混合表而不会丢失特定表中的ORDER。像这样：

id  |  num  |  TBL
 3  |    9  |    2
 4  |    7  |    1
 1  |    8  |    2
 1  |    4  |    1
 7  |    1  |    2

提前致谢！我感谢任何帮助！

Answer 1

如果要交错表格，则需要其他信息。如果枚举每一行，则可以使用它进行排序。像这样：

(SELECT e.id, e.num, '1' as TBL, (@rn1 := @rn1 + 1) as rn
 FROM events e CROSS JOIN
      (SELECT @rn1 := 0) vars
 ORDER BY e.num desc
)
UNION ALL
(SELECT p.id, p.num, '2' as TBL, (@rn2 := @rn2 + 1) as rn
 FROM places p CROSS JOIN
      (SELECT @rn2 := 0) vars
 ORDER BY p.num desc
)
ORDER BY rn, tbl desc;

Answer 2

试试这个：

DECLARE @t TABLE (rn INT IDENTITY,id INT,TBL INT)

INSERT INTO @t (id, TBL)
SELECT id,1 FROM events
INSERT INTO @t
SELECT id,2 FROM places

DECLARE @t2 TABLE (rn INT IDENTITY,num numeric(18,2))

INSERT INTO @t2 (num)
(
SELECT  num 
FROM events
UNION ALL
SELECT  num 
FROM places)
ORDER BY num DESC

SELECT id, num, TBL
FROM @t a
JOIN @t2 b ON a.rn = b.rn

SQL切换选择的偶数/奇数值

2 个答案: