Which SQL JOIN type returns all rows from the left table and the matched rows from the right table, with nulls when there is no match?

Which SQL JOIN type returns all rows from the left table and the matched rows from the right table, with nulls when there is no match?

• A. INNER JOIN returns all rows from the left and right tables regardless of matches.
• B. RIGHT JOIN returns all rows from the right table and the matched rows from the left table.
• C. LEFT JOIN returns all rows from the left table and the matched rows from the right table, with nulls when there is no match.
• D. FULL JOIN returns only nonmatching rows.

Answer: (C)

The concept being tested is how a left join works. A left join returns every row from the left table and brings in the matching data from the right table when a match exists; if there is no match, the right-side columns appear as nulls. This exactly matches the description: you get all rows from the left table, the matched right-side data when available, and nulls where there’s no right-side match. For example, if you list customers (left) and their orders (right), you'd see every customer, and for those with no orders you’d see nulls in the order fields. Inner join would drop left-side rows without a right-side match, right join would prioritize all rows from the right table, and full join would include all rows from both tables, with nulls where there’s no match—option that goes beyond what’s described.

The concept being tested is how a left join works. A left join returns every row from the left table and brings in the matching data from the right table when a match exists; if there is no match, the right-side columns appear as nulls. This exactly matches the description: you get all rows from the left table, the matched right-side data when available, and nulls where there’s no right-side match. For example, if you list customers (left) and their orders (right), you'd see every customer, and for those with no orders you’d see nulls in the order fields. Inner join would drop left-side rows without a right-side match, right join would prioritize all rows from the right table, and full join would include all rows from both tables, with nulls where there’s no match—option that goes beyond what’s described.