No. It is a fast syntax sanity check that looks for balanced quotes and parentheses, trailing commas, and a recognizable statement shape. It does not understand full MySQL grammar, check table or column names, or run your query.
Does my SQL get sent to a server or database?
No. The check runs entirely in your browser using JavaScript. Your SQL never leaves the page and the tool never connects to any database, so it is safe for private queries.
What kinds of problems can it catch?
Empty input, unbalanced parentheses, unterminated single quotes, double quotes, or backticks, trailing commas before FROM or a closing parenthesis or the end of the statement, statements that do not start with a recognized keyword, and a missing trailing semicolon (shown as a warning).
It says no problems found — does that mean my query is correct?
Not necessarily. A clean result only means the basic structure looks fine. Logic errors, wrong column names, and dialect-specific issues will not be caught — run the query against your actual database to be certain.