title: UNION before INNER JOIN
body: <p>Why when I use UNION before INNER JOIN like this</p>
  
  <pre><code>    select some_table1.some_column1,
             some_table1.some_column2
      FROM some_table1
      UNION ALL
      select some_table2.some_column1,
             some_table2.some_column2
      FROM some_table2
      INNER JOIN  some_table3
      ON  some_table3.some_column1 = some_table1.some_column1 
  </code></pre>
  
  <p>I have an eror: could not  bound multi-part identifer "some_table3.some_column1"?
  All data types are compatible.</p>