Does this check whether my tables and columns actually exist?

No — that requires a real database connection and schema, which is outside what a client-side tool can safely do. This checks the query's structure and syntax: balanced punctuation, clause order, and common shape mistakes that apply regardless of your actual schema.

Does it work for MySQL, PostgreSQL, and SQL Server alike?

Yes, for the checks it runs — parenthesis/quote balance, clause ordering (SELECT → FROM → WHERE → GROUP BY → HAVING → ORDER BY → LIMIT), and JOIN conditions are shared conventions across virtually every SQL dialect. It doesn't flag dialect-specific syntax errors, since what's valid varies between engines.

Why did it flag my JOIN when I'm sure it's correct?

A CROSS JOIN or NATURAL JOIN intentionally has no ON/USING clause, and this checker already accounts for those. If a plain JOIN, LEFT JOIN, or INNER JOIN is flagged, double-check that the ON or USING condition didn't get lost — it's one of the most common causes of an accidental cross-product in production queries.

Why does it ignore things inside string literals and comments?

A parenthesis, quote, or keyword inside a string literal ('SELECT this') or a comment (-- FROM here) isn't part of the query's actual structure, so counting it would produce false positives. The checker strips string and comment content before analyzing structure, the same way a real SQL parser would.

SQL VALIDATOR

Catch unbalanced parentheses, out-of-order clauses, trailing commas, and missing JOIN conditions before you run a query.

SQL

No common syntax issues found

This is a heuristic linter, not a full SQL parser — it catches common mistakes (unbalanced parentheses and quotes, out-of-order clauses, trailing commas, missing JOIN conditions) across most SQL dialects, but it doesn't validate table/column names or dialect-specific syntax.

How to validate a SQL query

1
Paste your SQL query.
2
The linter checks for unbalanced parentheses and quotes, out-of-order clauses, trailing commas, and JOINs missing an ON/USING condition.
3
Fix each flagged issue — errors are likely to break the query, warnings are worth a second look but may be intentional.

Questions

Does this check whether my tables and columns actually exist?: No — that requires a real database connection and schema, which is outside what a client-side tool can safely do. This checks the query's structure and syntax: balanced punctuation, clause order, and common shape mistakes that apply regardless of your actual schema.
Does it work for MySQL, PostgreSQL, and SQL Server alike?: Yes, for the checks it runs — parenthesis/quote balance, clause ordering (SELECT → FROM → WHERE → GROUP BY → HAVING → ORDER BY → LIMIT), and JOIN conditions are shared conventions across virtually every SQL dialect. It doesn't flag dialect-specific syntax errors, since what's valid varies between engines.
Why did it flag my JOIN when I'm sure it's correct?: A CROSS JOIN or NATURAL JOIN intentionally has no ON/USING clause, and this checker already accounts for those. If a plain JOIN, LEFT JOIN, or INNER JOIN is flagged, double-check that the ON or USING condition didn't get lost — it's one of the most common causes of an accidental cross-product in production queries.
Why does it ignore things inside string literals and comments?: A parenthesis, quote, or keyword inside a string literal ('SELECT this') or a comment (-- FROM here) isn't part of the query's actual structure, so counting it would produce false positives. The checker strips string and comment content before analyzing structure, the same way a real SQL parser would.