Download CS348 – INFORMATION SYSTEMS

CS348 – INFORMATION
SYSTEMS
Romila Pradhan
Introduction to JDBC
What is JDBC?
Java DataBase Connectivity
- Java API to access RDBMS
- Facilitates Java applications to:
- connect to a data source, e.g., a database
- send queries and update statements to the database
- retrieve and process the results
Architecture
Java Application
JDBC API
provides access to
relational data
from Java
JDBC Driver Manager
JDBC Driver
defines objects that
connect Java applications
to a JDBC driver
Oracle
Steps to process SQL statements
1.
2.
3.
4.
5.
Establish a connection
Create a statement
Execute the query
Process the ResultSet object
Close the connection
Sample Program
Download from
https://www.cs.purdue.edu/homes/rpradhan/cs348/s17/musicDB.java
1. Establish a connection
Connect to Oracle through a Connection object
Connection conn =
DriverManager.getConnection("jdbc:oracle:thin:@claros.cs.purdue.edu:1524:strep",
”USERNAME",”PASSWORD");
USERNAME: OracleAccount@csora
PASSWORD: OraclePassword
Compile and Run
Source the driver ($ORACLE_HOME/ojdbc6.jar)
Compile:
javac -cp $ORACLE_HOME/ojdbc6.jar musicDB.java
Run
java -cp .:$ORACLE_HOME/ojdbc6.jar musicDB
2. Create a statement
- An interface that represents a SQL statement.
- executing Statement objects,
- generate ResultSet objects
- Three different kinds of statements:
1. Statement: To implement SQL statements with no parameters
2. PreparedStatement: For precompiling SQL statements that might
contain input parameters
3. CallableStatement: To execute stored procedures that may contain
both input and output parameters
3. Execute the query
Three kinds of execute methods from Statement:
1. executeQuery
-
if the query retrieves some data from the database
returns one ResultSet object
2. executeUpdate
-
for SQL statements that update/modify the database
3. execute (can be used for any kind of SQL statement)
-
returns “true” if the SQL query was a SELECT
returns “false” if it was an UPDATE, INSERT or DELETE
4. Process the results
- Query results in a ResultSet object
- Access the data in a ResultSet object through a cursor
-
points to one row of data in the ResultSet object
NOT a database cursor
initially, the cursor is positioned before the first row
methods defined in the ResultSet object move the cursor
5. Close the connection
When you are finished using a Statement, call the method
Statement.close() to immediately release the resources
it is using
- the corresponding ResultSet objects are also closed
Recap: Steps to process SQL statements
1.
2.
3.
4.
5.
Establish a connection
Create a statement
Execute the query
Process the ResultSet object
Close the connection