MySQL SQL Validator — Check MySQL Syntax Online
Validate your MySQL queries before running them. This validator is preconfigured for MySQL dialect, catching syntax that works in other databases but fails in MySQL. It flags PostgreSQL operators like :: for type casting and ILIKE for case-insensitive matching, and warns about RETURNING clauses that MySQL does not support. Use it to validate application queries, migration scripts, and stored procedures before execution.
What This Tool Does
Validates MySQL SQL syntax in your browser and highlights errors with exact line numbers and descriptions — before you run queries against a live database.
Who This Is For
- MySQL developers and DBAs who want to catch syntax errors before execution to avoid downtime
- Backend engineers writing migration scripts who want a quick validation pass
- Learners practicing MySQL who need clear, specific error feedback as they write queries
- Anyone porting SQL from another dialect who needs to confirm MySQL compatibility
Example: Input: SELECT * FORM users WHERE id = 1 → Output: Error at line 1: "FORM" is not a valid MySQL keyword — did you mean FROM? with the exact character position highlighted
MySQL-Specific Validation
When the dialect is set to MySQL, the validator applies additional checks:
::operator — Flagged as invalid. MySQL usesCAST()orCONVERT()for type casting.ILIKE— Flagged as unsupported. MySQL'sLIKEoperator is case-insensitive with the default collation (utf8mb4_general_ci).RETURNING— Flagged as unsupported. UseSELECT LAST_INSERT_ID()after INSERT to get the generated ID.- Backtick identifiers — MySQL uses backticks (
`table_name`) for quoting identifiers, which differs from PostgreSQL's double quotes.
Common MySQL Mistakes
These are the most frequently encountered MySQL-specific issues:
- GROUP BY strictness — MySQL 5.7+ with
ONLY_FULL_GROUP_BYrequires that all non-aggregated columns in SELECT appear in GROUP BY. This catches many queries that worked in older MySQL versions. - String comparison — MySQL's default collation makes string comparisons case-insensitive. This surprises developers coming from PostgreSQL where comparisons are case-sensitive by default.
- LIMIT syntax — MySQL uses
LIMIT offset, countorLIMIT count OFFSET offset. The two-argument form puts offset first, which is the opposite of what many developers expect. - Reserved words — MySQL reserves words like
RANK,GROUPS, andSYSTEMthat may not be reserved in other databases. Quote them with backticks if used as identifiers.
MySQL vs PostgreSQL Compatibility
Porting SQL between MySQL and PostgreSQL is one of the most common migration tasks. Key differences that this validator helps catch:
- Type casting: MySQL
CAST(x AS UNSIGNED)vs PostgreSQLx::integer - String concatenation: MySQL
CONCAT(a, b)vs PostgreSQLa || b - Auto-increment: MySQL
AUTO_INCREMENTvs PostgreSQLSERIALorGENERATED ALWAYS AS IDENTITY - Boolean: MySQL treats
1/0as true/false; PostgreSQL has a nativeBOOLEANtype
🔒 Privacy & Security
Your SQL never leaves your browser. There is no server — all parsing, validation, formatting, and explanation happens in JavaScript running locally on your device. This means your table names, column names, query logic, and data patterns are never transmitted anywhere. You can disconnect from the internet after loading this page and the tool still works.
Frequently Asked Questions
SQL Tool Suite
Related Guides & Tutorials
SQL Validation: A Complete Guide
Learn how to validate SQL before execution across PostgreSQL, MySQL, and SQL Server.
TutorialHow to Validate SQL Queries Online
Step-by-step tutorial for catching syntax errors and dialect incompatibilities.
GuideUnderstanding SQL Queries
How query explainers parse SQL to produce summaries and complexity scores.
TutorialExplain SQL in Plain English
Step-by-step tutorial for getting plain English breakdowns of any SQL query.