Question

At least one type of phone is required, but some parents may not provide all types of phone numbers. What is the SQL statement to retrieve the phone numbers of parents who have provided at least one type of phone number?

Answer 1

To retrieve phone numbers of parents who have provided at least one type, an SQL query checks each phone number column for non-null values and selects rows meeting this criterion.

Step-by-step explanation:

The SQL statement to retrieve the phone numbers of parents who have provided at least one type of phone number would require checking each phone number column in the database and selecting the rows where at least one of these columns is not null. Assuming the database has separate columns for home, work, and mobile phone numbers, the SQL query would look something like:

SELECT ParentID, HomePhone, WorkPhone, MobilePhone
FROM Parents
WHERE HomePhone IS NOT NULL
OR WorkPhone IS NOT NULL
OR MobilePhone IS NOT NULL;

This query selects the parent's identifier and phone numbers from the table named Parents only for those rows where at least one of the phone number fields is not empty (null).