Inner vs Outer Joins: The Two Fundamental Join Types in SQL

SQL joins fall into two fundamental categories — inner joins and outer joins — while LEFT , RIGHT , and FULL joins are subclasses of the outer join. This hierarchy is defined by the logical principle of "which rows are included in the result set" and "which table's unmatched rows are preserved". The Two Fundamental Types Type Core Logic Result Set INNER JOIN "Match only — discard what doesn't match" Returns only rows that satisfy the join condition in both tables. OUTER JOIN "Keep one side as th