这是表格:TABLE1
ID | id_activity | id_elem | text
---------------------------------------
1 | 1 | 11 | text1 |
2 | 1 | 12 | text2 |
3 | 1 | 13 | text3 |
4 | 2 | 11 | text4 |
5 | 2 | 12 | text5 |
6 | 2 | 13 | text6 |
7 | 3 | 11 | text7 |
8 | 3 | 12 | text8 |
9 | 3 | 13 | text9 |
10 | 4 | 11 | text10 |
11 | 4 | 12 | text11 |
12 | 4 | 13 | text12 |
13 | 5 | 11 | text13 |
14 | 5 | 12 | text14 |
15 | 5 | 13 | text15 |
16 | 6 | 11 | text16 |
17 | 6 | 12 | text17 |
18 | 6 | 13 | text18 |
我需要得到这样的结果:
ID | text_elem_11 | text_elem_12 | text_elem_13
---------------------------------------------------
1 | text1 | text2 | text3 |
2 | text4 | text5 | text6 |
3 | text7 | text8 | text9 |
4 | text10 | text11 | text12 |
5 | text13 | text14 | text15 |
6 | text16 | text17 | text18 |
执行此操作的正确方法是什么?通过以下查询,我只能获得包含第一列和第二列的表格
SELECT table1.ID,
table1.id_elem,
elem_11.text AS text_elem_11
FROM table1
INNER JOIN table1 AS elem_11 ON
table1.id_activity = 1 AND
table1.id_elem = 11 AND
elem_11.id_elem = 11
这就是结果
id_activity | id_elem | text_elem_11 |
-----------------------------------------
1 | 11 | text1 |
1 | 11 | text4 |
1 | 11 | text7 |
我不知道如何添加其他 2 列,如果使用单个查询来完成它是一个好主意...那么,有什么想法吗?
最佳答案
SELECT id_activity,
MAX(CASE WHEN id_elem = 11 THEN text END) text_elem_11,
MAX(CASE WHEN id_elem = 12 THEN text END) text_elem_12,
MAX(CASE WHEN id_elem = 13 THEN text END) text_elem_13
FROM TableName
GROUP BY id_activity
ORDER BY id_activity
输出
╔═════════════╦══════════════╦══════════════╦══════════════╗
║ ID_ACTIVITY ║ TEXT_ELEM_11 ║ TEXT_ELEM_12 ║ TEXT_ELEM_13 ║
╠═════════════╬══════════════╬══════════════╬══════════════╣
║ 1 ║ text1 ║ text2 ║ text3 ║
║ 2 ║ text4 ║ text5 ║ text6 ║
║ 3 ║ text7 ║ text8 ║ text9 ║
║ 4 ║ text10 ║ text11 ║ text12 ║
║ 5 ║ text13 ║ text14 ║ text15 ║
║ 6 ║ text16 ║ text17 ║ text18 ║
╚═════════════╩══════════════╩══════════════╩══════════════╝
如果您的 id_elem
数量未知,则更首选动态 sql,
SET @sql = NULL;
SELECT GROUP_CONCAT(DISTINCT
CONCAT('MAX(CASE WHEN id_elem = ',
id_elem,
' THEN text ELSE NULL END) AS ',
CONCAT('`text_elem_' , id_elem, '`')
)) INTO @sql
FROM TableName
ORDER BY id_elem;
SET @sql = CONCAT('SELECT id_activity, ', @sql, '
FROM TableName
GROUP BY id_activity
ORDER BY id_activity');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
关于php - 使用mysql将表的列划分为不同的行,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16445774/