title: Change value in child table if parent table record meets condition
body: <p>If i have a table</p>
  
  <pre><code>parent_table {ID,code} 
  </code></pre>
  
  <p>2 colums. <code>ID</code> - primary key</p>
  
  <pre><code>childe_table {ID,parent_table_ID, Name} 
  </code></pre>
  
  <p>3 columns. <code>parent_table_id</code> is foreign key</p>
  
  <p>I'm trying to create query to do this:</p>
  
  <pre><code>if(parent_table.code == 'x'){
      child_table.Name == 'value'
  }
  </code></pre>
  
  <p>I know that I should use joins to do this.
  Could someone show me an example?</p>