計算在mysql中具有相同值的行，然后顯示項目號

Question

我有以下數據，希望能將它們分組。

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

我想將以下內容組合到此輸出中：

| 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    |

那有可能嗎？ 到目前為止，這是我嘗試過的

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

我得到的輸出是

| 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    |

第二個數字沒有增加。

Answer 1

這是MySQL。 您只需要正確執行變量算術：

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為您要在每行上重新設置計數器變量。 因此，它從1到"" ，並且空字符串被視為0-因此，在下一次安裝時，它將增加到1。依此類推。

Answer 2

嘗試這個：

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