MySQL GROUP_CONCAT 不返回所有结果

Question

我使用 GROUP_CONCAT 来获得由逗号分割的结果( , )，但是当我看到时， GRUP_CONCAT仅返回 205 拆分的数字，但在数据库中有 2448 结果(不同 aid )。这是我的查询:

SELECT GROUP_CONCAT(`aid`) As favoriti 
FROM `z_web_favoriti` 
WHERE `kup_id`='1' AND `pos_id`='571'

当我执行:

SELECT DISTINCT `aid` 
FROM `z_web_favoriti` 
WHERE `kup_id`='1' AND `pos_id`='571'

我得到以下结果:显示第 0 - 29 行(总共 2448 行，..)

任何人都有一些解决方案，为什么它不起作用？
我在stackoverflow上搜索过类似的问题，但我找不到它..

Answer 1

可能你已经超过GROUP_CONCAT最大长度。

The result is truncated to the maximum length that is given by the group_concat_max_len system variable, which has a default value of 1024. The value can be set higher, although the effective maximum length of the return value is constrained by the value of max_allowed_packet. The syntax to change the value of group_concat_max_len at runtime is as follows, where val is an unsigned integer:

SET [GLOBAL | SESSION] group_concat_max_len = val;