Getting Started with IBM Data Studio for DB2

238 Getting Started with IBM Data Studio for DB2
8.1 Stored procedures: The big picture
Stored procedures can help improve application performance and reduce database access
traffic. All database access must go across the network, which, in some cases, can result
in poor performance. Figure 8.1 illustrates the stored procedure data flow..
Figure 8.1 Stored procedure data flow
As shown in Figure 8.1, an application must initiate a separate communication with the
DB2 database server for each SQL statement. So, SQL #1, SQL #2, and SQL #3 require
individual communication traffic.
To improve application performance, you can create stored procedures that run on your
database server. A client application can then simply call the stored procedures
(MYPROC in Figure 8.1) to obtain results of all the SQL statements that are contained in
the stored procedures. Because a stored procedure runs the SQL statements on the
server for you, the overall performance is improved. In addition, stored procedures can
help to centralize business logic. If you make changes to a stored procedure, the changes
are immediately available to all client applications.
Stored procedures are also very useful when deleting or updating large numbers of rows.
You can specify a cursor in a stored procedure, and then loop through the result and
delete or update rows. This reduces locking activity and is useful in an OLTP environment.
8.2 Steps to create a stored procedure
The recommended perspective for stored procedure development is the IBM SQL and
Routine Development perspective. To switch to this perspective, select Window -> Open
Perspective -> Other -> IBM SQL and Routine Development from the main menu.
As discussed in Chapter 5, you must create a data development project to store routines.
Each data development project is associated with a single database connection. In this
chapter, we’ll be connecting to theGSDB sample database that has been used in previous