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

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

• A. LEFT OUTER JOIN
• B. INNER JOIN
• C. RIGHT OUTER JOIN
• D. FULL OUTER JOIN

Answer: (A)

To keep every row from the left table while pulling in matching data from the right, and to show nulls where there isn’t a match, you use a left outer join. This preserves all records from the left side and fills in right-side columns with nulls when there’s no corresponding row on the right. An inner join would drop left rows without a match, a right outer join would preserve all rows from the right, and a full outer join would keep all rows from both sides with nulls where there are no matches. So, left outer join is the behavior described.

To keep every row from the left table while pulling in matching data from the right, and to show nulls where there isn’t a match, you use a left outer join. This preserves all records from the left side and fills in right-side columns with nulls when there’s no corresponding row on the right. An inner join would drop left rows without a match, a right outer join would preserve all rows from the right, and a full outer join would keep all rows from both sides with nulls where there are no matches. So, left outer join is the behavior described.