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Editor to share with you how to modify the length limit of the group_conca function in mysql. I hope you will gain a lot after reading this article. Let's discuss it together.

In mysql, there is a function called "group_concat". If you use it normally, you may not find a problem. When dealing with big data, you will find that the content has been intercepted.

In fact, MYSQL has a setting for this. By default, the length not set is 1024. If we need larger, we need to modify it manually.

The details are as follows:

After using group_concat, it will not work if limit is used in select.

There is a length limit when connecting fields with group_concat, not how many connections there are. But you can set it up.

Using the group_concat_max_len system variable, you can set the maximum length allowed.

The default delimiter for the system is a comma

Modification method:

SET [SESSION | GLOBAL] group_concat_max_len = 10240

Parameters that can be modified are as follows

GROUP_CONCAT accumulates the values of a field by a specified character. The default delimiter is a comma, and the character length that can be accumulated is 1024 bytes.

1. Let's give a simple example.

Select group_concat (favoa) from t_one group by fimb

Group the query by fallob, and accumulate the fancia in each group.

2. Modify the default delimiter

Select group_concat (fancia separator'_') from t_one group by fimb

Separator is a keyword, followed by a character to be separated

3. Sort

Select group_concat (order by order by favob separator'_') from t_one group by fumb

4. Modify the default character size

1) add to the MySQL configuration file

Group_concat_max_len = 102400 # the maximum length you want

2) it can be simple, execute the statement, and set the scope of action.

SET GLOBAL group_concat_max_len=102400; SET SESSION group_concat_max_len=102400

5. And concat use

Group_concat returns BLOB large objects by default. You can use concat to return strings and add other data to the returned content.

After reading this article, I believe you have a certain understanding of how to modify the length limit of the group_conca function in mysql. If you want to know more about it, welcome to follow the industry information channel. Thank you for reading!

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