SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 4)
    Identifier b.name (alias name)
    Identifier a.a_col (alias a_col)
    Identifier b.b_col (alias b_col)
    Function if (alias some_val) (children 1)
     ExpressionList (children 3)
      Literal UInt64_1
      Literal \'N\'
      Identifier b.some_val
   TablesInSelectQuery (children 2)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier test_a_table (alias a)
    TablesInSelectQueryElement (children 2)
     TableExpression (children 1)
      TableIdentifier test_b_table (alias b)
     TableJoin (children 1)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier a.name
        Identifier b.name
   Function equals (children 1)
    ExpressionList (children 2)
     Identifier b.some_val
     Literal \'Y\'
