1. Client Access, Queries, Stored Procedures, JDBC
CS 433 DB2 Overview
Client Access, Queries, Stored Procedures, JDBC
9/12/01
Jeff Derstadt & Megha Batra

2. Administration Project Proposals Due 09/14/01 by 5PM Email them to TAs
Please register your group on the web

3. Client Configuration Must setup a client-server connection
Server name:
egret.csuglab.cornell.edu
Port:
50000
Database name:
Your group (g7, g23, etc.)

4. Client Configuration
Let’s configure our client!

5. Command Line Queries Connect to database Issue queries
Connect to <database_name> user <user_name> using <password>
Issue queries
CREATE TABLE <table> (<column_name> <datatype>, …)
INSERT INTO <table> values (…)
SELECT <columns> from <table>

6. Command Line Queries
Let’s issue some queries!

7. Stored Procedures Definition: Examples:
A set of SQL and programming language (C++/Java) statements that are compiled into a named database object that can be invoked by a user application
Examples:
For each sailor with a rating less than 5, insert her into the “NeedsTraining” table, and her requesting that she sign up for additional instruction
Converting relational tables to Xml

8. Stored Procedures (2) Advantages
Can embed SQL in a ‘native’ programming language
Executed on the database server: no network delay
Compiled procedures can be invoked by any user application
Provides consistent functionality (don’t need to rewrite SQL ‘inserts’, can just call a stored procedure)

9. Java DB2 allows you to write stored procedures in Java
+ Java is an easy language
- Must use some sort of bridge between the native DB2 code and the Java Virtual Machine to transfer data from a relational table to the stored procedure
+/- JDBC provides this bridge: extra copy, but easy access

10. DB2 to Java 3 1 2 Java Virtual Machine Int sid = rs.getInt(1);
String name = rs.getString(2); 3
ResultSet
rs;
Result extracted from JDBC
DB2
(C++)
SID=5, NAME=Sarah
Query Result 1
JDBC (Java Database Connection) 2
Copy from DB2 to JDBC storage

11. JDBC java.sql.* Using JDBC adds additional costs However
Copy from DB2 to JDBC ResultSet object (2)
Copy from ResultSet object to another Java variable (sometimes at 3)
However
JDBC makes issuing SQL queries and gathering results very easy

12. JDBC ResultSet Provides a simple cursor object
A cursor is a set-of-records abstraction that allows you to move from one row to the next and access the columns:
SID
NAME
rs.next()
rs.getString(2) 12
Sarah 13
Joe 15
Megha

13. Stored Procedures
Let’s write a stored procedure that converts a table to Xml!

14. Questions ??