计算在mysql中具有相同值的行，然后显示项目号

Question

我有以下数据，希望能将它们分组。

|       Label             |     Category        |
|   PC Equipment          |     Materials       |
|   PC Equipment          |     Materials       |
|   PC Equipment - Install|     Installation    |
|   Table Setup           |     Materials       |
|   Table Setup           |     Materials       |
|   Table Setup - Install |     Installation    |

我想将以下内容组合到此输出中：

| Item #|       Label             |     Category        |
|       |   PC Equipment          |     Materials       |
|       |   PC Equipment          |     Materials       |
|   1   |   PC Equipment - Install|     Installation    |
|       |   Table Setup           |     Materials       |
|       |   Table Setup           |     Materials       |
|   2   |   Table Setup - Install |     Installation    |

那有可能吗？ 到目前为止，这是我尝试过的

SELECT
    @row_number := CASE WHEN Label LIKE "%Install%" THEN @row_number + 1 
                        ELSE "" 
                   END AS row_number,
    Label       
FROM table1 t,
    (SELECT @rownum := 0) r
WHERE deleted = 0

我得到的输出是

| Item #|       Label             |     Category        |
|       |   PC Equipment          |     Materials       |
|       |   PC Equipment          |     Materials       |
|   1   |   PC Equipment - Install|     Installation    |
|       |   Table Setup           |     Materials       |
|       |   Table Setup           |     Materials       |
|   1   |   Table Setup - Install |     Installation    |

第二个数字没有增加。

Answer 1

这是MySQL。 您只需要正确执行变量算术：

SELECT (CASE WHEN Label LIKE '%Install%'
             THEN cast(@icnt := @icnt + 1 as char(10))
             ELSE ''
        END) AS row_number,
       Label       
FROM table1 t CROSS JOIN
     (SELECT @icnt := 0) params
WHERE deleted = 0;

您的方法不起作用的原因是因为您要在每行上重新设置计数器变量。 因此，它从1到"" ，并且空字符串被视为0-因此，在下一次安装时，它将增加到1。依此类推。

Answer 2

尝试这个：

SELECT IF(Label LIKE "%Install%", rn, '') AS 'Item #',
       Label, Category
FROM (
  SELECT @row_number := CASE 
                           WHEN Label LIKE "%Install%" THEN @row_number + 1
                           ELSE @row_number
                        END AS rn,
         Label, Category
  FROM table1 AS t
  (SELECT @row_number := 0) AS r
  WHERE deleted = 0
  ORDER BY Label) AS t