What is the difference between WHERE and HAVING?

WHERE filters individual rows before grouping, while HAVING filters groups after aggregation. You use HAVING to keep, for example, only the groups whose COUNT(*) is greater than five, which WHERE cannot do because the aggregate is not yet computed.

How does pagination differ across databases?

MySQL, PostgreSQL and SQLite use LIMIT n OFFSET m. SQL Server uses TOP n, or OFFSET ... FETCH NEXT for paging. Oracle uses FETCH FIRST n ROWS ONLY. The cheatsheet flags these differences in the LIMIT entry.

What is an upsert and how do I write one?

An upsert inserts a row or updates it if a key already exists. PostgreSQL and SQLite use INSERT ... ON CONFLICT DO UPDATE, MySQL uses INSERT ... ON DUPLICATE KEY UPDATE, and SQL Server uses the MERGE statement.

In what order does a SELECT actually run?

Although you write SELECT first, the logical order is FROM, then WHERE, then GROUP BY, then HAVING, then SELECT, then ORDER BY, then LIMIT. This is why a column alias defined in SELECT cannot be used in WHERE but can be used in ORDER BY.

Is anything I search uploaded?

No. The reference and the search both run entirely in your browser. This tool does not connect to any database or send your input anywhere.

SQL Syntax Cheatsheet

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This is a searchable SQL syntax cheatsheet covering the keywords, clauses and functions you use every day. Each entry gives the syntax pattern, a one-line description, and — where the dialects diverge — notes for MySQL, PostgreSQL, SQLite and SQL Server, so you can write portable queries or adapt one to a specific engine.

How it works

SQL is largely standardised by ANSI, but every database adds its own spellings for common tasks. The reference is grouped so you can browse by area: Query (SELECT, DISTINCT, CTEs), Clause (WHERE, GROUP BY, HAVING, ORDER BY, LIMIT), Join types, DML (INSERT, UPDATE, DELETE, upsert), DDL (CREATE, ALTER, DROP, indexes), aggregate and scalar functions, window functions and transactions. Search matches the keyword, the syntax and the dialect notes, so a query for “pagination” or “auto increment” surfaces the right entries even if you do not remember the exact keyword.

Tips and gotchas

The single most useful thing to internalise is the logical execution order of a SELECT: FROM → WHERE → GROUP BY → HAVING → SELECT → ORDER BY → LIMIT. It explains why you cannot reference a SELECT alias inside WHERE, and why aggregate filters belong in HAVING. Watch the dialect notes for the big traps: FULL OUTER JOIN is missing in MySQL and SQLite, auto-increment is spelled four different ways, and upsert syntax differs by engine. Everything runs in your browser; this tool never connects to a database or uploads your input.