How can constraints be utilized to address the issue of preventing the last admin user from losing admin privileges in PHP user administration?

To prevent the last admin user from losing admin privileges in PHP user administration, we can utilize constraints in our database schema. One approach is to add a constraint that ensures there is always at least one admin user in the database, preventing the last admin user from being demoted.

// Add a constraint to the database schema to prevent the last admin user from losing admin privileges
ALTER TABLE users
ADD CONSTRAINT at_least_one_admin CHECK (SUM(CASE WHEN role = 'admin' THEN 1 ELSE 0 END) >= 1);