February 23rd, 2003, 07:01 PM
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MySQL and Connector/J
Hello All,
I've got a MySQL 4.0.10(Gamma) database running with a table called demo in a database called emp.
I'm attempting to use the Connector/J 3.0.6 to get data from the database in a Java application, eventually i'll be using Servlets, but for now I'm just attempting to get anything to work.
I'm using the following code:
Code:
//Program1.java
// the very simplest JDBC program
// make JDBC package available
import java.sql.*;
class Program1 {
public static void main(String argv[]) {
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
//Connect to MySQL giving user id and password
String connectionURL = "jdbc:mysql://localhost:3306/emp";
Connection connection = null;
connection = DriverManager.getConnection(connectionURL,"root","");
// set up and execute SQL retrieval statement
Statement stmt = connection.createStatement();
String SQLStatement = "SELECT * FROM emp.demo";
ResultSet rs = stmt.executeQuery(SQLStatement);
// move to first row of result set
rs.next();
// extract name from first row and print
String theName = rs.getString("name");
System.out.println("the name is : " + theName);
// tidy up and disconnect
rs.close();
stmt.close();
connection.close();
} catch( ClassNotFoundException e ) {
// print trace of error
System.err.println("Couldn't find the the MySQL " + "database driver: " + e.getMessage());
} catch( Exception e){
e.printStackTrace();
}
}
}
I've got J2SE 1.4.0 and J2EE 1.3 installed the code above compiles without a problem but on execution i get:
Code:
C:\Java>java Program1
Exception in thread "main" java.lang.NoClassDefFoundError: Program1
C:\Java>
I'm new to this whole databases aspect of Java so any help would be great!
Thanks in advance everyone!
Chris
February 24th, 2003, 12:49 PM
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It probably cannot find the com.mysql.jdbc.Driver object. Make sure this is in your classpath. To run a program in main, you can assign it to the CLASSPATH environment variable or you can set it at execution time using this on the command line:
Code:
java Program1 -cp c:\where\the\jar\file\is\mysqldriver.jar
When doing this in your servlet you want to make sure the jar file is in WEB-INF/lib.
Hope this helps