SQLEXISTSsubquerytutorial

What is EXISTS in SQL? Existence check for beginners

EXISTS asks "is there at least one row matching the condition?". Plain words: a filter on the presence of a related record (e.g. "customers with at least one order"), the difference from IN with a subquery, NOT EXISTS, and NULL behavior.

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EXISTS is the check "is there at least one row matching the condition?". Returns TRUE or FALSE. Used in WHERE to filter "rows that have a related record".

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