Final answer:
To ensure that a query returns only a single element, the 'limit' or 'top' operator should be used in the SQL query, depending on the database system. These operators are coupled with 'ORDER BY' to sort rows before limiting the output.
Step-by-step explanation:
If a user requires that a query only return a single element, the operator that should be used is commonly known as the limit or top operator, depending on the database management system in use. In SQL, the SELECT TOP operator is used in Microsoft SQL Server, while the LIMIT clause is used in MySQL, PostgreSQL, and SQLite to fetch a defined number of records. It's important to note that when these operators are used, they are typically coupled with an ORDER BY clause to ensure that the rows are sorted before the limit is applied, so that the most relevant row(s) are returned.
The LIMIT operator is used in SQL to limit the number of records returned in a query result. It specifies the maximum number of rows to return from the result set.
For example, if a user wants to retrieve only the first 3 records from a table, the query would be:
SELECT * FROM table_name LIMIT 3;
This will return only 3 rows from the table, regardless of how many rows match the query criteria.