Question

我有多个表，每个表中都有Nr_Crt作为自动增量。我能够显示查询结果但我的问题是这样的：表1

nr_crt |item
     1 |item 1
     2 |item 2
     3 |item 3

和表2

nr_crt |item
     1 |song 1
     2 |song 2
     3 |song 3.

有没有办法像这样显示结果？

Nr. | Product
  1 |item 1
  2 |item 2
  3 |item 3
  4 |song 1
  5 |song 2
  6 |song 3

我知道我必须使用SELECT COUNT（*）FROM ..... 谢谢。

Answer 1

这应该这样做：

SELECT @row := @row + 1 AS nr, 
       a.val            AS product 
FROM   (SELECT item AS val 
        FROM   table1 
        UNION ALL 
        SELECT item 
        FROM   table2) a 
       JOIN (SELECT @row := 0) r

<强>结果

| NR | PRODUCT |
----------------
|  1 |  item 1 |
|  2 |  item 2 |
|  3 |  item 3 |
|  4 |  song 1 |
|  5 |  song 2 |
|  6 |  song 3 |

See the demo

Answer 2

SELECT  @rnk := @rnk + 1 nr_crt,
        a.item
FROM
        (
            SELECT  nr_crt, item, 1 ordr FROM TableA
            UNION ALL
            SELECT  nr_crt, item, 2 ordr FROM TableA
        ) a, (SELECT @rnk := 0) b
ORDER   BY a.ordr ASC, a.nr_crt ASC

SQLFiddle Demo

输出

╔════════╦════════╗
║ NR_CRT ║  ITEM  ║
╠════════╬════════╣
║      1 ║ item 1 ║
║      2 ║ item 2 ║
║      3 ║ item 3 ║
║      4 ║ item 1 ║
║      5 ║ item 2 ║
║      6 ║ item 3 ║
╚════════╩════════╝

计算所有表中的行并在增量之前显示

2 个答案: