mysql - group_concat 不显示所有值 mysql

Question

ModelName.all(:having=>"count(receipt_no)>1",:select=>"school_id,group_concat(id SEPARATOR ',') as f_ids,receipt_no,count(distinct id) as id_count,count(receipt_no) as  rec_count",:conditions=>"receipt_no is not null",:group=>"receipt_no")

输出是

 +------------+-----------+----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----------+
| receipt_no | school_id | id_count | f_ids                                                                                                                                                                               | rec_count |
+------------+-----------+----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-----------+
| 1261       | 1783      | 2        | 557660,557661                                                                                                                                                                       | 2         |
| 14/15-     | 1783      | 1209     | 68352,77056,113664,56320,68353,77057,113665,56321,68354,56322,68355,81923,173571,113667,56323,68356,94980,56324,68357,56325,68358,80390,56326,68359,80391,110599,56327,80392,885... | 1209      |
| 15-        | 1783      | 112      | 344067,344068,344069,344070,344075,326923,373261,373262,345882,360218,344091,361755,347685,341542,347689,360233,351530,358705,352829,324674,341576,324684,360018,368469,371541,3... | 112       |

这里的group_concat并没有显示所有的值，而是显示项目的计数与计数收据编号相同。假设 f_ids 列中的项目超过 200 个字符，那么它不会显示所有值。在其他情况下，它将显示正确的值

Answer 1

我得到了解决方案

SET SESSION group_concat_max_len = 1000000;

在 MySQL 控制台中运行这段代码，然后这段代码会将默认的 group_concat 字符限制更改为 1000000 个字符。

如果你想在rails console中使用，你可以通过以下方式使用

sql = "SET SESSION group_concat_max_len = 1000000"
ActiveRecord::Base.connection.execute(sql)

请注意:此配置仅在该 session 中有效