title: Create a check constraint that a value exists in another table
body: <p>I'm using a mariaDB instance and I would like to create a check constraint that a value must exist in another table. In the below example, TableA.Number must already exist in TableB.</p>
  <h2>TableA</h2>
  <p>Name varchar(30)</p>
  <p>Number int</p>
  <h2>TableB</h2>
  <p>Number int</p>