Database execution cost and system performance estimator

Claim 1

A tool, for use in a computer system, for estimating execution costs of at least a portion of an application having at least one query statement for accessing a database; said tool comprising: a user interface for receiving input from a user corresponding to a partial definition of at least one table in said database; means for building a simplified query statement, said simplified query statement having a place-holder for each expression detail within said at least one query statement, using at least one of said at least one table; and means, based on said simplified query statement for estimating a cost of executing said at least one query statement against said database; wherein the simplified query statement comprises only those portions of the query statement that are essential in determining the execution costs of the application accessing the database with said query statement taking into consideration a first input by the user of an estimate of a number of rows resulting in an execution of the query statement, and a second input by the user of an estimate of a number of pages touched and an estimate of a number of pages read.