A Level Computer Science OCR Practice Exam

Which symbol is used in SQL to represent a logical OR operation?

1. ∧

2. ∨

3. ¬

4. ⊕

The correct answer is: ∨

In SQL, the logical OR operation is represented by the symbol '∨'. This symbol allows for the combination of multiple conditions, where the overall expression evaluates to true if at least one of the individual conditions is true. For example, in a SQL query, using the OR operator would look something like this: ```sql SELECT * FROM students WHERE age < 18 OR grade = 'A'; ``` In this example, the query will return any student who is either under the age of 18 or has a grade of 'A'. It enables flexible querying by allowing you to specify alternative criteria. The other symbols presented do not serve the purpose of a logical OR in SQL. The symbol for AND (∧) would be used to require both conditions to be true, while the negation operator (¬) represents logical NOT, which reverses the truth value of a condition. The final symbol (⊕) typically denotes exclusive OR in logic, which is not the same as standard OR and would not be used in SQL for this purpose.