Index[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] nested "containers" nested interval model (SQL trees) nested loops 2nd 3rd 4th nested queries in from clause nested set model (SQL trees) 2nd aggregating values stored in leaf nodes bottom-up tree walk top-down walk network problems insufficient speed or bandwidth "next value to use" table nine situations nodes relational view of a tree tree representing a hierarchy non-linear sensitivity to data volume increases non-relational layer of SQL limiting thickness of OLAP functions normalization atomicity checking attribute independence checking dependence on the whole key data warehousing and 3NF design ensuring atomicity not exists ( ), using with a correlated subquery not in ( ), using with uncorrelated subquery 2nd 3rd null returns null values 2nd numerical values, comparing |