SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 1)
    Identifier concat(str, \'_abc\')
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Subquery (children 1)
       SelectWithUnionQuery (children 1)
        ExpressionList (children 1)
         SelectQuery (children 2)
          ExpressionList (children 1)
           Literal \'string\' (alias str)
          ExpressionList (children 1)
           Function concat (children 1)
            ExpressionList (children 2)
             Identifier str
             Literal \'_abc\'