Hello, It is known that the MySQL codebase suffers from numerous unforseen interactions between components, so that if we have a query X that works when executed stand-alone, it may still break if it is executed as, for example, INSERT ... SELECT . So, the Random Query Generator has a module that runs each generated query into different contexts. Here is the current list: - as CREATE|INSERT|REPLACE ... SELECT - as a prepared statement, twice - as a stored procedure, twice - as a UNION - converted into a VIEW The question is, what else is missing? I know about the following: - DELETE/UPDATE, etc. operations that involve the query as a subquery - triggers but what about trying to evaluate the query inside an IF, CASE, FOR , or anything else? If you have any suspicion that any of the code handles a particular situation or context differently, please let me know so that I can add it to the RQG. Thank you. Philip Stoev