SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 6)
   ExpressionList (children 2)
    Identifier a
    Function count (children 1)
     ExpressionList
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier pr_t
   ExpressionList (children 2)
    Identifier a
    Identifier b
   ExpressionList (children 1)
    OrderByElement (children 1)
     Identifier a
   Literal UInt64_500
   Literal UInt64_5
