Question

The ON clause can be used only if the tables being joined have a common column with the same name.

a) TRUE
b) FALSE
c) NOT NULL
d) UNIQUE

Answer 1

The statement about the ON clause requiring common column names in both tables for a join is FALSE. The ON clause specifies join conditions and can use columns with different names, as long as they contain related data.

Step-by-step explanation:

The statement “The ON clause can be used only if the tables being joined have a common column with the same name” is FALSE. The ON clause in SQL is used to specify the conditions for a join and does not require the column names to be the same in both tables. It is perfectly valid to join tables using columns with different names but related data.

For example, if you are joining a table of employees and a table of departments, you might have a “empleado_id” column in the employees table and a “manager_id” column in the departments table. You can join these two tables using the ON clause as follows:

SELECT * FROM employees e JOIN departments d ON e.empleado_id = d.manager_id;

This query would allow you to match rows where the employee is the manager of a department, demonstrating the flexibility of the ON clause.