________ checks to see if programs that are interdependent actually work together as planned.

A placeholder for unknown characters in the criteria of a query is called a(n) ________

Fill in the blank(s) with correct word

Consider a three-tiered system interfacing to a centralized DBMS, in which n1 presentation servers are connected to n2 application servers, which in turn are connected to n3 transaction servers. Assume that for each transaction, the application server, on average, invokes k procedures, each of which is executed on an arbitrary transaction server, and that each procedure, on average, executes s SQL statements that must be processed by the DBMS. If, on average, a presentation server handles r requests per second (each request produces exactly one transaction at the application server), howmany SQL statements per second are processed by the DBMS and how many messages flowover each communication line?

What will be an ideal response?