MySQL return different string based on values in table columns

Question

I have the following function that I created for pulling a user's preferred name:

public function getPreferredName($unique_id) {

    $sql = "SELECT CONCAT(first_name, ' ', last_name) as name FROM `{$this->table}` WHERE `unique_id` = ? LIMIT 1";
    $stmt = $this->pdo->prepare($sql);
    $stmt->execute([$unique_id]);

    if ($stmt->rowCount() == 0) return null;

    $preferredName = $stmt->fetchColumn();

    return $preferredName;

}

This table is a "users" table made up of individuals and companies.

There are some additional fields that I would like to consider in this query:

• "display_as" (individual or company)
• "company_name" (used when display_as = company)

Now i'd like to modify the method above to return either the first and last name OR the company name based on whether the value of the "display_as" column equals "individual" or "company".

If "display_as" equals "individual" return the first_name and last_name fields.

If "display_as" equals "company" return the company_name field.

How can I modify the method above to return either the first_name and last_name together or the company_name value based on the "display_as" column?

Thanks for the help. Cheers

Answer 1

You can use the MySQL IF function for this:

$sql = "Select If(`display_as` = 'individual',
        CONCAT(IFNULL(first_name,''), ' ', IFNULL(last_name,''))
       ,`company_name`) as name FROM `{$this->table}` WHERE `unique_id` = ? LIMIT 1";

This works because you have only two options, individual or company.
If you have more options you will have to use case when construct.