In SQL, <> is the ANSI-standard “not equal” comparison operator that returns TRUE when two expressions differ.
The <> operator denotes “not equal to.” It evaluates two expressions and returns TRUE when they differ and FALSE when they are identical. All major SQL engines support it.
<> is ANSI-standard, while != is a vendor extension found in MySQL, SQL Server, and others. Prefer <> for maximum portability across databases.
Use <> for direct value comparison (price <> 0). Use NOT to negate predicates such as NOT EXISTS or NOT IN. Matching the operator to intent improves clarity.
To exclude refunded orders: SELECT * FROM orders WHERE status <> 'refunded'; The query returns only active transactions.
No. Any comparison with NULL using <> yields UNKNOWN, behaving like FALSE in WHERE clauses. Use IS NULL or IS NOT NULL instead.
Inequality can still use B-tree indexes if the predicate leaves a sargable range, but expect fewer index seeks than with equality checks.
Handle NULL explicitly, favor <> over != for portability, and benchmark queries on large tables to avoid unexpected full scans.
Update only changed rows: UPDATE products SET price = 9.99 WHERE price <> 9.99; This avoids unnecessary writes and trigger executions.
Inequality checks drive critical logic, from filtering bad data to enforcing incremental updates. Misusing the <> operator can degrade performance, break NULL semantics, or cause cross-database bugs. Mastering its behavior helps data engineers write portable, efficient, and correct SQL across diverse warehouses.
Yes. <> is defined by the ANSI SQL specification and is portable across databases.
Absolutely. As long as both expressions are comparable, <> can evaluate numeric, text, date, and boolean types.
Galaxy’s AI Copilot autocompletes inequality predicates, flags NULL traps, and lets you benchmark <> queries directly in its desktop SQL editor.
Performance depends on indexes and data distribution. Benchmark both; <> is usually faster for simple scalar comparisons.
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