title: Get number of rows when a value for a whole database
body: <p>I have a hypothetical database with 1000 tables. Some tables have a field called <code>person_id</code>. I want to find out how many of rows in the <strong>entire</strong> database that has a value of <code>10</code> for every table that has the field <code>person_id</code> without writing a query for every table. Is this possible to do in a single SQL statement?</p>