Explain EXPLAIN (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 4)
    ExpressionList (children 1)
     Identifier b.bx
    TablesInSelectQuery (children 4)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier a
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       Subquery (alias b) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 2)
           ExpressionList (children 2)
            Identifier b1
            Function concat (alias bx) (children 1)
             ExpressionList (children 2)
              Identifier b2
              Literal \'x\'
           TablesInSelectQuery (children 1)
            TablesInSelectQueryElement (children 1)
             TableExpression (children 1)
              TableIdentifier b
      TableJoin (children 1)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier b.b1
         Identifier a.a1
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       TableIdentifier c
      TableJoin (children 1)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier c.c1
         Identifier b.b1
     TablesInSelectQueryElement (children 2)
      TableExpression (children 1)
       Subquery (alias d) (children 1)
        SelectWithUnionQuery (children 1)
         ExpressionList (children 1)
          SelectQuery (children 2)
           ExpressionList (children 1)
            Identifier number (alias d1)
           TablesInSelectQuery (children 1)
            TablesInSelectQueryElement (children 1)
             TableExpression (children 1)
              Function numbers (children 1)
               ExpressionList (children 1)
                Literal UInt64_10
      TableJoin (children 1)
       Function equals (children 1)
        ExpressionList (children 2)
         Identifier d.d1
         Identifier c.c1
    Function notEquals (children 1)
     ExpressionList (children 2)
      Identifier c.c2
      Literal \'\'
    ExpressionList (children 1)
     OrderByElement (children 1)
      Identifier a.a2
