MySQL, Java, and JDBC CSE 3330 Southern Methodist University

Question When’s the last time you pulled up Amazon.com and typed in an SQL Query directly? How about with Access.SMU? Issued any SQL Queries directly recently?

Accessing MySQL We need a way to access from a programming languages Various ways to do this in different languages Java uses the JDBC API – JDBC = Java Database Connectivity – Allows standardized access to relational databases from Java

Overview Java-based Application MySQL Connector/J MySQL DBMS

JDBC JDBC standardizes: – Initiating a connection to a RDBMS – Creating a SQL statement for later execution – Executing a SQL statement against the RDBMS – Retrieving the result of a query (if applicable) MySQL’s Connector/J – Type 4 JDBC Driver – All Java/Native protocol driver

JDBC Some Important JDBC API classes: – Driver Manager – Connection – Statement – ResultSet – SQLException

In your IDE Create a new Project called JDBCTest Add MySql JDBC Driver to your “libraries” that are used in compiling – In Netbeans, go to project properties, choose libraries on left, and select the aforementioned driver Create an empty Java source file – import java.sql.*; – add a main method to the file.

public static void main (String [] args) { try { Class.forName("com.mysql.jdbc.Driver"); Connection conn = DriverManager.getConnection( "jdbc:mysql://localhost/cse3330a?”+ “user=root&password=aSecret123" ); Statement stmt = conn.createStatement(); ResultSetrs = stmt.executeQuery("SELECT * FROM classes"); while (rs.next()){ System.out.println(rs.getString("prof")); } rs.close(); stmt.close(); conn.close(); } catch (Exception e) { System.out.println(e.getMessage()); } Overview DOES NOT WORK; Get Main.java example From

Step 1) Load the MySQL JDBC Driver Class.forName("com.mysql.jdbc.Driver");

Step 2) Create a Connection Connection conn = DriverManager.getConnection( "jdbc:mysql://localhost/cse3330a?”+ “user=root&password=aSecret123”); Server Database Username Password

Step 3) Create Statement and Execute SQL Query Statement stmt = conn.createStatement(); ResultSetrs = stmt.executeQuery( "SELECT * FROM classes");

Step 4) Iterate over Results Imagine result set is a “table” or grid with each column having a name while (rs.next()){ System.out.println(rs.getString("prof")); }

Step 5) Clean Up rs.close(); stmt.close(); conn.close(); Note – Reverse Order

In-Class Exercise Write a program that will: – Allow the user to enter their student id – Show a list of classes to the user (SELECT) – Allow the user to “register” for a class (INSERT) Log in to MySQL directly to make sure the insert took place. Don’t worry about details like double registering or overlapping times (esp. since we’re not storing times)