Transcript Introduction to JDBC

Introduction to JDBC
Michelle Lee, Ye Wu & Jeff Offutt
http://www.cs.gmu.edu/~offutt/
SWE 432
Design and Implementation of Software for the Web
JDBC
• JDBC (Java Database Connectivity) API allows Java
programs to connect to databases
• Database access is the same for all database vendors
• The JVM uses a JDBC driver to translate generalized
JDBC calls into vendor specific database calls
• There are four general types of JDBC drivers
– We will look at Type 4 …
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Pure Java Driver (Type 4)
• These drivers convert the JDBC API calls to direct
network calls using vendor-specific networking protocols
by making direct socket connections with the database
• It is the most efficient method to access database, both in
performance and development time
• It is the simplest to deploy
• All major database vendors provide pure Java JDBC
drivers for their databases and they are also available from
third party vendors
• For a list of JDBC drivers, refer to
– http://industry.java.sun.com/products/jdbc/drivers
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Pure Java Driver (2)
DB Client
Java
Application
Server
Data Source
JDBC
API
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JDBC Driver
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Typical JDBC Programming Procedure
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Load the database driver
Obtain a connection
Create and execute statements (SQL queries)
Use result sets (tables) to navigate through the results
Close the connection
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Driver Manager
• The purpose of the java.sql.DriverManger class in
JDBC is to provide a common access layer on top of
different database drivers used in an application
• DriverManager requires that each driver required by the
application must be registered before use, so that the
DriverManager is aware of it
• Load the database driver using ClassLoader :
– Class.forName (“oracle.jdbc.driver.OracleDriver”);
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Connecting to a Database
• Type 4 JDBC Driver – Oracle Server
Class.forName (“oracle.jdbc.driver.OracleDriver”);
con = DriverManager.getConnection (
“jdbc:oracle:thin:@bonsai.ite.gmu.edu:1521:ite”,
“accountname", “password”);
• Type 4 JDBC Driver – MySQL Server
Class.forName (“org.gjt.mm.mysql.Driver”);
con = DriverManager.getConnection
(“jdbc:mysql://localhost/databasename”, uid, passwd);
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Creating Tables
• Creating a Coffee table
CREATE TABLE COFFEES (COF_NAME VARCHAR(32), SUP_ID
INTEGER, PRICE FLOAT, SALES INTEGER, TOTAL INTEGER)
• Creating JDBC statements
SQL query
Statement stmt = con.createStatement ();
• Execute a statement
stmt.executeUpdate (“CREATE TABLE COFFEES “ +
“(COF_NAME VARCHAR(32), SUP_ID INTEGER,
PRICE FLOAT, “ + “SALES INTEGER, TOTAL
INTEGER)”);
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Execute Statements
• This uses executeUpdate because the SQL statement
contained in createTableCoffees is a DDL (data
definition language) statement
• Statements that create a table, alter a table, or drop a table
are all examples of DDL statements and are executed with
the method executeUpdate
• executeUpdate is also used to execute SQL statements
that update a table
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Execute Statements
• In practice, executeUpdate is used far more often to
update tables than it is to create them because a table is
created once but may be updated many times
• The method used most often for executing SQL statements
is executeQuery
• executeQuery is used to execute SELECT statements,
which comprise the vast majority of SQL statements
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Entering Data into a Table
Statement stmt = con.createStatement();
stmt.executeUpdate ( "INSERT INTO COFFEES " +
"VALUES ('Colombian', 101, 7.99, 0, 0)");
stmt.executeUpdate ( "INSERT INTO COFFEES " +
"VALUES ('French_Roast', 49, 8.99, 0, 0)" );
stmt.executeUpdate ( "INSERT INTO COFFEES " +
"VALUES ('Espresso', 150, 9.99, 0, 0)" );
stmt.executeUpdate ( "INSERT INTO COFFEES " +
"VALUES ('Colombian_Decaf', 101, 8.99, 0, 0)" );
stmt.executeUpdate ( "INSERT INTO COFFEES " +
"VALUES ('French_Roast_Decaf', 49, 9.99, 0, 0)" );
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Getting Data From a Table
ResultSet rs = stmt.executeQuery ("SELECT COF_NAME, PRICE
FROM COFFEES");
while (rs.next())
{
String s = rs.getString ("COF_NAME");
float n = rs.getFloat ("PRICE");
System.out.println (s + " " + n);
}
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JDBC Data Source Architecture
JDBC
Application
Database
JNDI
Connection Manager
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Sample code
• Sun JDBC tutorial
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