Question

我有一个项目表（如下所示）

+------+--------+-------+-----------+-----------+--------+
| prod | period | group | item_code | prop_code | value  |
+------+--------+-------+-----------+-----------+--------+
|    3 | 199901 |     1 |       101 |         1 |  16240 |
|    3 | 199902 |     2 |       102 |         2 |   6142 |
|    3 | 199903 |     1 |       105 |         3 |    340 |
|    3 | 199904 |     1 |       106 |         4 |   5003 |
|    3 | 199905 |     1 |       201 |         5 |   3544 |
|    3 | 199906 |     1 |       202 |         6 |     13 |
|    3 | 199907 |     1 |       206 |         7 |      9 |
|    3 | 199908 |     1 |       301 |         8 |     64 |
|    3 | 199909 |     2 |       302 |         9 |  30408 |
|    3 | 199910 |     2 |       303 |        10 |    740 |
|    3 | 199911 |     1 |       304 |        11 |    660 |
|    3 | 199912 |     1 |       305 |        12 |   1113 |
|    4 | 200001 |     1 |       306 |        13 | 298881 |
|    4 | 200002 |     2 |       307 |        14 | 186097 |
|    4 | 200003 |     1 |       402 |        15 |    600 |
|    4 | 200004 |     2 |       403 |        16 | 164765 |
|    4 | 200005 |     2 |       404 |        17 | 203938 |
|    4 | 200006 |     2 |       405 |        18 |    195 |
|    4 | 200007 |     1 |       406 |        19 |     80 |
|    4 | 200008 |     2 |       409 |        20 |    970 |
|    4 | 200009 |     1 |       502 |        21 |  89012 |
|    4 | 200010 |     1 |       602 |        22 |  47473 |
|    4 | 200011 |     2 |       603 |        23 |    775 |
|    4 | 200012 |     1 |       604 |        24 |    335 |
+------+--------+-------+-----------+-----------+--------+

我正在尝试动态地将行更改为“＃period; period＆＃39;将列在列和各自的值＃39;将会在＆＃39;期间？像这样 -

| prod | group | item_code | prop_code | 199901 | 199902 | 199903 | 199904 | 199905 | 199906 | 199907 | 199908 | 199909 | 199910 | 199911 | 199912 | 200001 | 200002 | 200003 | 200004 | 200005 | 200006 | 200007 | 200008 | 200009 | 200010 | 200011 | 200012 |

非常感谢任何帮助。

Answer 1

看起来你已经遇到了GROUP_CONCAT的最大长度，长度为1024个字符。您可以使用此SET SESSION group_concat_max_len来增加其长度

SET SESSION group_concat_max_len = 1000000;
SET @sql = NULL; 
SELECT GROUP_CONCAT(DISTINCT CONCAT( 'MAX(CASE WHEN period = ', period, ' then value ELSE NULL end) AS period', period, '') ) INTO @sql FROM items; 
SET @sql = CONCAT('SELECT prod,`group`,item_code,prop_code, ', @sql, ' FROM items GROUP BY prod,`group`,item_code,prop_code'); 
PREPARE stmt FROM @sql;
EXECUTE stmt; 
DEALLOCATE PREPARE stmt;

sqlfiddle

Mysql，动态地将行转换为列

1 个答案: