Explain EXPLAIN SYNTAX (children 1)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Asterisk
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       Subquery (alias outer_table_alias) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 2)
           ExpressionList (children 2)
            Function toUInt64 (alias a) (children 1)
             ExpressionList (children 1)
              Identifier b
            Function sum (alias b) (children 1)
             ExpressionList (children 1)
              Identifier id
           TablesInSelectQuery (children 1)
            TablesInSelectQueryElement (children 1)
             TableExpression (children 1)
              TableIdentifier test_00597 (alias table_alias)
    Function equals (children 1)
     ExpressionList (children 2)
      Identifier outer_table_alias.b
      Literal UInt64_3
