A Level Computer Science OCR Practice Exam

What does the wildcard character (*) in SQL indicate?

1. Specific fields in a query

2. All records in a query

3. Filtered results

4. Count of all records

The correct answer is: All records in a query

The wildcard character (*) in SQL is used to represent all records or all fields in a query, which is why it is the correct answer. When you use the asterisk in a SELECT statement, for instance, it instructs the database to return every column from the specified table. For example, the query `SELECT * FROM employees;` retrieves all data from the 'employees' table, regardless of the number of columns or the amount of data in those columns. This functionality is particularly useful when you want to perform operations on all fields without needing to specify them individually. It's a convenient way to select data when the specific structure of the table is either unknown or when you require all available information for your analysis or processing. Overusing the wildcard can lead to inefficient queries, especially with large datasets, but it remains a fundamental feature in SQL for retrieving comprehensive data sets quickly.