SQL Query Validator

Runs in browser Database

A dialect-aware structural validator for SQL: keyword order, clause structure, balanced parentheses and quotes, missing WHERE in UPDATE/DELETE, SELECT * warnings and injection-prone concatenation.

Privacy: This tool runs entirely in your browser. Your input never leaves your device.

How to use SQL Query Validator

  1. Paste one or more statements separated by semicolons.
  2. Pick the dialect.
  3. Review the issue table — errors block execution, warnings are risky patterns, hints are style advice.

SQL Query Validator features

  • Lexical checks: unterminated strings, comments and quoted identifiers
  • Balanced parentheses and CASE … END pairs, trailing commas, dangling operators
  • Clause order for SELECT (FROM → WHERE → GROUP BY → HAVING → ORDER BY → LIMIT)
  • Safety warnings: UPDATE/DELETE without WHERE, JOIN without ON, "= NULL"
  • INSERT column/value count mismatches
  • Injection smells: string concatenation with variables, OR 1=1 tautologies
  • Dialect hints (LIMIT vs TOP, backticks vs brackets)

SQL Query Validator example

Catch a clause-order mistake

Input:

SELECT * FROM users ORDER BY id WHERE active = 1

Output:

ERROR line 1: WHERE appears after ORDER BY; the expected order is SELECT → FROM → WHERE → GROUP BY → HAVING → WINDOW → ORDER BY → LIMIT.
INFO line 1: SELECT * returns every column.

Frequently asked questions about SQL Query Validator

Does it connect to my database?

No. Validation is purely structural and runs in your browser: it checks quotes, parentheses, clause order and dangerous patterns, but it cannot know whether tables and columns exist.

What kinds of problems does it detect?

Unterminated strings and comments, unbalanced parentheses, clauses in the wrong order (e.g. WHERE after ORDER BY), trailing commas, dangling operators, INSERT column/value count mismatches, missing WHERE on UPDATE/DELETE, JOINs without ON, "= NULL" comparisons and dialect-specific syntax such as LIMIT in SQL Server.

What is the injection warning?

It flags string literals concatenated with variables ('…' + @user), tautologies such as OR 1=1 and payload-like literals. Use bound parameters instead of building SQL from strings.

Can I validate multiple statements?

Yes. Statements are split on semicolons and each is reported with its own index, type and issues.

Technical notes

Because the validator does not know your schema, it cannot report unknown tables or columns. It is a fast first line of defence for hand-written queries, code review and CI checks on migration scripts.