SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 2)
    Identifier left.x
    Function CAST (children 1)
     ExpressionList (children 2)
      Function isNull (children 1)
       ExpressionList (children 1)
        Identifier right.x
      Literal \'Boolean\'
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier left
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier right
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier left.x
        Identifier right.x
