Explain EXPLAIN QUERY TREE (children 2)
 Set
 SelectWithUnionQuery (children 1)
  ExpressionList (children 1)
   SelectQuery (children 3)
    ExpressionList (children 1)
     Function count (children 1)
      ExpressionList
    TablesInSelectQuery (children 1)
     TablesInSelectQueryElement (children 1)
      TableExpression (children 1)
       TableIdentifier x
    Function and (children 1)
     ExpressionList (children 2)
      Identifier A
      Function or (children 1)
       ExpressionList (children 2)
        Function and (children 1)
         ExpressionList (children 2)
          Identifier B
          Identifier C
        Function or (children 1)
         ExpressionList (children 2)
          Function and (children 1)
           ExpressionList (children 2)
            Identifier B
            Identifier D
          Function and (children 1)
           ExpressionList (children 2)
            Identifier B
            Identifier E
