Column mixed up when using JSON_ARRAYAGG

[kobyan]

I encountered a situation where some of the column values ​​in my output csv file were defined in other columns. That is, I ran with columns -C id,login,pass,data, and in the output file for some of the lines the result was id,login,data,pass, and for some - id,login,pass,data.
The reason for this is that in UNION based injections using JSON_ARRAYAGG, the column values ​​are connected via CONCAT_WS. But if one of the column values ​​is NULL, CONCAT_WS simply skips it and does not add a separator string after it. Therefore, the column values ​​are mixed up in the resulting csv file. When dumping a large number of columns, this can create complete chaos in the result.

To solve this problem, it makes sense to do processing for the columns via IFNULL. (IFNULL(<column>, 0x20))