A database for web applications should be fast, simple, and reliable.
MySQL1 is an open source database designed for web applications by prioritizing speed and simplicity over larding it down with every feature of the SQL standard. PostgreSQL, another popular database for web applications, was designed to be more fully SQL-compliant so it has views, stored procedures, and triggers while MySQL doesn’t.
MySQL creates one thread per connection while PostgreSQL creates one process per connection, so MySQL uses less memory and works better for simple read-heavy applications like a web app.
MySQL was designed to be fast and simple for web applications. If you need advanced SQL features, use PostgreSQL.