APARs listed for a specific component apply only to that component.Other APARs apply to Cognos BI Server and may also apply to other components.Subqueries, or nested queries, are used to bring back a set of rows to be used by the parent query.Depending on how the subquery is written, it can be executed once for the parent query or it can be executed once for each row returned by the parent query.If the subquery is executed for each row of the parent, this is called a correlated subquery.A correlated subquery can be easily identified if it contains any references to the parent subquery columns in its WHERE clause.
Thus the view can insulate users from the effects of restructuring and growth in the database.
System R was designed and developed over a period of 1974-79 at IBM San Jose Research Center.
It is a prototype and its purpose was to demonstrate that it is possible to build a Relational System that can be used in a real life environment to solve real life problems, with performance at least comparable to that of existing system.
Then this is known as developing an artificial key.
A RDBMS maintains a description of all the data that it contains, information about every relation and index that it contains.