Explain EXPLAIN QUERY TREE (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 4)
    ExpressionList (children 4)
     Identifier x
     Function max (alias mA) (children 1)
      ExpressionList (children 1)
       Identifier A
     Function max (alias mB) (children 1)
      ExpressionList (children 1)
       Identifier B
     Function max (alias mC) (children 1)
      ExpressionList (children 1)
       Identifier C
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier x
    ExpressionList (children 1)
     Identifier x
    Function or (children 1)
     ExpressionList (children 2)
      Function and (children 1)
       ExpressionList (children 2)
        Identifier mA
        Identifier mB
      Function and (children 1)
       ExpressionList (children 2)
        Identifier mA
        Identifier mC
