Summit CPA Review
ISC SQL · Updated November 2026

SQL Joins on ISC: Which Rows Actually Survive?

Do not memorize JOIN syntax before understanding which unmatched records must remain in the result.

INNER JOIN

Returns records with matches in both tables. Think only matched pairs.

LEFT JOIN

Returns all rows from the left table and matched rows from the right. Unmatched right-side values become null.

RIGHT JOIN

Uses the same concept while preserving all rows from the right table.

FULL OUTER JOIN

Returns matched rows plus unmatched rows from both sides.

Keys

Primary keys uniquely identify records and foreign keys connect related tables.

The takeaway

Ask which table's unmatched records must survive. Then choose the JOIN.

Related Summit guides

WHERE vs HAVINGContinue with a related Summit CPA Review guide.Keys and normalizationContinue with a related Summit CPA Review guide.Data lifecycleContinue with a related Summit CPA Review guide.

FAQ

Does INNER JOIN keep unmatched rows?

No.

Does LEFT JOIN keep every left-side row?

Yes.

Do I need advanced SQL coding?

Focus on the level required by the current Blueprint and review materials.