SQL Validator
Check a SQL statement for structural problems such as unbalanced parentheses, unterminated strings or comments, and an unrecognised leading command, for PostgreSQL, MySQL, SQLite or T-SQL, locally in your browser.
- Runs locally in your browser
- No upload required
Try it
Supported formats
Privacy
Runs entirely in your browser. Your input is never uploaded, stored, or sent to a third party.
No structural error found (0 finding(s) reported).
How it works
- Tokenised the SQL, keeping literals, identifiers and comments opaque.
- Checked parenthesis depth and string/comment terminators.
- Classified the leading keyword of each top-level statement.
- Warnings do not make the statement invalid; only error-severity findings do.
Methodology
- Tokenise the statement, treating strings, quoted identifiers and comments as opaque so their contents are never mis-read.
- Track parenthesis depth and quote/comment terminators, naming each structural problem with an offset.
- Identify the leading command keyword of every top-level statement and flag an unrecognised one as a warning.
Usage
- Paste a SQL statement or script.
- Choose the dialect whose lexical rules should apply.
- Run the validator and read the named findings; a clean result means no structural problem was found.
Examples
These are examples, not current values: they use fixed inputs, while the interactive tool computes live results in your browser.
A valid SELECT
{
"text": "select id, name from users where id = 1;",
"dialect": "standard"
}Unbalanced parenthesis
{
"text": "select count(*) from users where (id = 1;",
"dialect": "postgresql"
}MySQL backtick identifier
{
"text": "select `full name` from `users`;",
"dialect": "mysql"
}Limitations
Structural checks, not a schema check
A validator can see delimiters, quotes and comments; it cannot know your tables or columns. Treat a clean result as one gate among several before you run anything against a real database.
Dialects change the rules
MySQL accepts backtick identifiers and backslash escapes; T-SQL uses square brackets; PostgreSQL adds dollar-quoted strings. Choosing the right dialect keeps the validation honest.
Frequently asked questions
- Does a clean result mean the query will run?
- No. It means the statement is structurally sound for the chosen dialect; it does not check your schema, permissions or functions.
- Which dialects are supported?
- PostgreSQL, MySQL, SQLite and T-SQL, plus a generic standard mode for dialect-neutral SQL.
- Is my SQL uploaded?
- No. The statement is validated entirely in your browser and is never sent anywhere.
Sources
- ISO/IEC 9075-1:2023: Information technology, Database languages SQL — ISO/IEC
- PostgreSQL Documentation: SQL Syntax, Lexical Structure — PostgreSQL Global Development Group
- MySQL 8.0 Reference Manual: String Literals — Oracle
- SQLite Documentation: SQL Syntax — SQLite Consortium
- Microsoft Learn: Transact-SQL Syntax Conventions — Microsoft
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