SQL Validator
Free online SQL validator. Check SQL syntax and find errors before executing. Works with MySQL, PostgreSQL, SQLite and SQL Server. Catch mistakes early. All processing is local and private.
Paste SQL and click "Validate" to check for errors.
How to Use SQL Validator
Paste Your SQL
Paste a SQL query or script into the input panel. The tool accepts any SQL dialect — MySQL, PostgreSQL, SQLite, SQL Server. Multi-statement scripts with semicolons are supported.
Validate the Syntax
Click "Validate" to check for syntax errors. The validator checks balanced parentheses, proper keyword usage, missing clauses, and common SQL mistakes. Errors are shown with line numbers.
Fix Errors
Review each error and fix it in the input panel. Click "Validate" again to confirm the fix. Repeat until your SQL is clean before executing against a real database.
Common SQL Errors Detected
| Error | Fix |
|---|---|
| Unmatched parentheses | Count opening and closing parens — they must match |
| Missing FROM clause | SELECT requires FROM (unless selecting literals) |
| JOIN without ON | Add ON or USING to specify join condition |
| Unclosed string literal | Strings must have matching single quotes |
| Trailing comma in SELECT | Remove comma before FROM clause |
Frequently Asked Questions
What does the validator check?
Our validator checks: balanced parentheses and quotes, that required SQL keywords are present (FROM after SELECT, etc.), that JOINs have ON/USING clauses, that GROUP BY columns are properly referenced, common syntax errors like missing commas or semicolons, and basic SQL structure. It does NOT check: whether tables or columns actually exist (that requires a database connection), type compatibility between expressions, or the semantic correctness of your query logic.
Does it work with all SQL dialects?
The validator handles common SQL syntax shared across MySQL, PostgreSQL, SQLite, and SQL Server — SELECT, INSERT, UPDATE, DELETE, CREATE TABLE, JOINs, subqueries, CTEs (WITH clauses), window functions, and common data types. Dialect-specific features (like PostgreSQL's :: cast syntax, MySQL's backtick quoting, or SQL Server's square bracket identifiers) are recognized but may not be fully validated. The validator errs on the side of accepting valid dialect-specific syntax rather than flagging false positives.
Can I validate multi-statement scripts?
Yes. Separate statements with semicolons and the validator checks each one independently. This is useful for migration files, seed scripts, and SQL dumps that contain multiple CREATE, INSERT, and ALTER statements. Statements are split on semicolons that appear outside of string literals.
How is this different from running EXPLAIN or checking in a database?
Our validator is a static syntax checker — it runs entirely in the browser with no database connection. It catches syntax errors before you send SQL to a database, where a typo could cause unexpected behavior or data loss. For semantic validation (do these columns exist? is this join logically correct?), use your database's EXPLAIN or query planner. For formatting, use our SQL Formatter. For minification, use the SQL Minifier.
SQL Validation Best Practices
Validating SQL before execution prevents errors that could corrupt data, return wrong results, or crash your application. A static syntax check catches the most common mistakes without needing a database connection.
- Validate early: Check SQL as soon as you write it, not after deploying to production
- Validate after edits: A working query can break with a single misplaced comma — re-validate after every change
- Combine with formatting: Use SQL Formatter to beautify, then Validator to check syntax
- Test with real data: Static validation catches syntax errors but not logic errors — always test against staging data