These functions of the Valentina extension for PHP are included only for compatibility with MYSQL interface. They do nothing - only return TRUE value. This guarantees that your script will not fail - but, otherwise, the script after DONOTHING function call logically would work improperly.
So, if you are migrating to Valentina Server from another database, remember to exclude these functions calls from your solutions.
Here is complete list of the DONOTHING functions: