Final answer:
The INNER JOIN is more restrictive in SQL because it only returns records with matching values in both tables, leading to fewer records if there aren't matches for every record in one table.
Step-by-step explanation:
In SQL, the INNER JOIN is typically more restrictive compared to OUTER JOINS (LEFT, RIGHT, FULL). An INNER JOIN will only return records that have matching values in both tables being joined, thus likely returning fewer records if not all records in one table have corresponding matches in the other.On the other hand, an OUTER JOIN will include all records from one table and the matched records from the other table. If the record from one table does not have a match in the other, the result will still show the record with NULLs for the missing matches.A LEFT JOIN is considered less restrictive than an INNER JOIN because it returns all records from the left table and the matched records from the right table.
The RIGHT JOIN behaves similarly but for the right table. A FULL OUTER JOIN is the least restrictive, returning all records when there is a match in either left or right table.In terms of JOIN operations in a database, the INNER JOIN is more restrictive compared to the OUTER JOIN. The INNER JOIN only returns records that have matching values in both tables being joined, resulting in fewer records being returned. On the other hand, the OUTER JOIN returns all records from one table and the matching records from the other table, so it is less restrictive and is likely to return more records.