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

Processed entirely in your browser; never uploaded.

Each dialect has its own comment, string and identifier rules.

Result
Valid
Findings
0
Errors
0
No structural problems found.

Supported formats

Input
text/plain
Output
text

Privacy

Runs entirely in your browser. Your input is never uploaded, stored, or sent to a third party.

Processing
In your browser
Privacy level
Browser only

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

  1. Tokenise the statement, treating strings, quoted identifiers and comments as opaque so their contents are never mis-read.
  2. Track parenthesis depth and quote/comment terminators, naming each structural problem with an offset.
  3. Identify the leading command keyword of every top-level statement and flag an unrecognised one as a warning.

Usage

  1. Paste a SQL statement or script.
  2. Choose the dialect whose lexical rules should apply.
  3. 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

jsonSelect to copy
{
  "text": "select id, name from users where id = 1;",
  "dialect": "standard"
}

Unbalanced parenthesis

jsonSelect to copy
{
  "text": "select count(*) from users where (id = 1;",
  "dialect": "postgresql"
}

MySQL backtick identifier

jsonSelect to copy
{
  "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

  1. ISO/IEC 9075-1:2023: Information technology, Database languages SQL — ISO/IEC
  2. PostgreSQL Documentation: SQL Syntax, Lexical Structure — PostgreSQL Global Development Group
  3. MySQL 8.0 Reference Manual: String Literals — Oracle
  4. SQLite Documentation: SQL Syntax — SQLite Consortium
  5. Microsoft Learn: Transact-SQL Syntax Conventions — Microsoft