Explain EXPLAIN (children 2)
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 2)
    ExpressionList (children 1)
     Asterisk
    TablesInSelectQuery (children 3)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier 03667_t1 (alias s)
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       Subquery (alias r) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 2)
           ExpressionList (children 1)
            Asterisk
           TablesInSelectQuery (children 1)
            TablesInSelectQueryElement (children 1)
             TableExpression (children 1)
              TableIdentifier 03667_t2
      TableJoin (children 1)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier s.key
         Identifier r.key
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       Subquery (alias c) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 2)
           ExpressionList (children 1)
            Asterisk
           TablesInSelectQuery (children 1)
            TablesInSelectQueryElement (children 1)
             TableExpression (children 1)
              TableIdentifier 03667_t3
      TableJoin (children 1)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier s.key
         Identifier c.key
 Identifier Null
