In Mysql Perpared statement increase the set variable length

Question

    set @sql1 = '';

    SELECT
      GROUP_CONCAT(DISTINCT
        CONCAT(
          'MAX(IF(field_id = ''',
          field_id,
          ''', value, NULL)) AS `',
          field_id,'`'
        )
      ) INTO @sql1
    FROM content_details;
    SET @sql1 = CONCAT('SELECT  ', @sql1, ' FROM content_details GROUP BY content_id');
    select @sql1;
    PREPARE stmt FROM @sql1;
    EXECUTE stmt;
    DEALLOCATE PREPARE stmt;
    

In above code @sql1 variable storing some limited characters only. Here I am concating string dynamically. I donot know the exact total length of the string what will come future. my question is how we can set the unlimited char length to the $sql1 variable. Please advice.

Answer 1

It sounds like you are having an issue with the GROUP_CONCAT_MAX_LEN. You can adjust the length of this variable during your session.

The default length of this variable is 1024. You should be able to use:

set session group_concat_max_len = yourNewValue;

If you were to set this globally it would impact all other connections, that is why you might only want to set it for your session.