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Assignment 17 Java to MySQL Connection

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Lab Assignment 17
Objective 1: Java to MySQL Connection (Using the JDBC-ODBC bridge)
Problem Statement:- A Java program for MySQL Connection
Explanation/Steps:-
We will first be creating a table in mysql for our example:
Create database Toy;
CREATE TABLE `humans` (
`ID` int(10) unsigned NOT NULL AUTO_INCREMENT,
`LastName` varchar(90) NOT NULL,
`FirstName` varchar(90) NOT NULL,
`Gender` varchar(90) NOT NULL,
`Address` varchar(255) NOT NULL,
`Phone` varchar(45) NOT NULL,
PRIMARY KEY (`ID`)
)
• Database will contain all the tables present in an application.
First import the necessary libraries for Database connection, java.sql:
import java.sql.*;
These are the necessary tools we will need:
Connection – This represents the connection to a specific database. This is used to establish the
connection with the database drive.
Statement – This is used to execute the SQL statement.
ResultSet – This holds the table of the data that is generated from a sql statement. For statements other
than select, this is not necessary used since the statement would not return a table. Then instantiate your
connection variables
Connection con;
Statement stmt;
ResultSet rs;
create an exception handler
try{
//Your Code Goes Here
}catch(Exception e){
System.err.println(e);
}
To make your exception handling more specific, you can add 2 more catch before Exception containing
SQLException and ClassNotFoundException
In the try block, insert your connection code, First is the forced loading of the Database Driver in
Class.forName() followed by the declaration of objects we instantiated earlier.
//Load the JdbcOdbc Driver
Class.forName(“com.mysql.jdbc.Driver”);
//Specify the Database URL where the DNS will be and the user and password
con = DriverManager.getConnection(“jdbc:mysql://localhost:3306/Toy”,”username”,”password”);
//Initialize the statement to be used, specify if rows are scrollable
stmt=con.createStatement();
//ResultSet will hold the data retrieved
rs = stmt.executeQuery(“SELECT * FROM Humans”);
Then we now get the data from the ResultSet object
//Display the results
while(rs.next()){
System.out.println(rs.getInt(“ID”) + ” ” + rs.getString(“LastName”) + ” ” +
rs.getString(“FirstName”));
}
OR
while(rs.next()){
System.out.println(rs.getInt(1) + ” ” + rs.getString(2) + ” ” + rs.getString(3));
}
*Note: You can use the column name or the column position to retrieve values from the resultset.
• For further reference for insert update and delete you can click here.
For a full source code listing:
import java.sql.*;
public class ViewingMySQL {
public static void main(String[] args) {
Connection con;
Statement stmt;
ResultSet rs;
try{
Class.forName(“com.mysql.jdbc.Driver “);
con = driverManager.getConnection(“”jdbc:mysql://localhost:3306/Toy”,”username”,”password”);
stmt = con.createStatement();
while(rs.next()){
System.out.println(rs.getInt(“ID”) + ” ” + rs.getString(“LastName”) + ” ” +
rs.getString(“FirstName”));
}
}catch(Exception e){
System.err.println(e);
}
}
}
Sample code:-
//STEP 1. Import required packages
import java.sql.*;
public class FirstExample {
// JDBC driver name and database URL
static final String JDBC_DRIVER = “com.mysql.jdbc.Driver”;
static final String DB_URL = “jdbc:mysql://localhost/EMP”;
// Database credentials
static final String USER = “username”;
static final String PASS = “password”;
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
try{
//STEP 2: Register JDBC driver
Class.forName(“com.mysql.jdbc.Driver”);
//STEP 3: Open a connection
System.out.println(“Connecting to database…”);
conn = DriverManager.getConnection(DB_URL,USER,PASS);
//STEP 4: Execute a query
System.out.println(“Creating statement…”);
stmt = conn.createStatement();
String sql;
sql = “SELECT id, first, last, age FROM Employees”;
ResultSet rs = stmt.executeQuery(sql);
//STEP 5: Extract data from result set
while(rs.next()){
//Retrieve by column name
int id = rs.getInt(“id”);
int age = rs.getInt(“age”);
String first = rs.getString(“first”);
String last = rs.getString(“last”);
//Display values
System.out.print(“ID: ” + id);
System.out.print(“, Age: ” + age);
System.out.print(“, First: ” + first);
System.out.println(“, Last: ” + last);
}
//STEP 6: Clean-up environment
rs.close();
stmt.close();
conn.close();
}catch(SQLException se){
//Handle errors for JDBC
se.printStackTrace();
}catch(Exception e){
//Handle errors for Class.forName
e.printStackTrace();
}finally{
//finally block used to close resources
try{
if(stmt!=null)
stmt.close();
}catch(SQLException se2){
}// nothing we can do
try{
if(conn!=null)
conn.close();
}catch(SQLException se){
se.printStackTrace();
}//end finally try
}//end try
System.out.println(“Goodbye!”);
}//end main
}//end FirstExample
Objective 2: Sample JDBC Program for Excel
Problem Statement:- A Java program for Excel database.
Code/Explanation:-
import java.sql.*; // Use classes in java.sql package
public class ExcelSelectTest {
public static void main(String[] args) {
try (
// Step 1: Allocate a database “Connection” object
Connection conn = DriverManager.getConnection(
“jdbc:odbc:ebookshopODBC”); // Access/Excel
// Step 2: Allocate a “Statement” object in the Connection
Statement stmt = conn.createStatement();
) {
// Excel connection, by default, is read-only.
// Need to turn it off to issue INSERT, UPDATE, …
conn.setReadOnly(false);
// Step 3: Execute a SQL SELECT query, the query result
// is returned in a “ResultSet” object.
// Table name is the sheet’s name in the form of [sheet-name$]
String strSelect = “select title, price, qty from [books$]”;
System.out.println(“The SQL query is: ” + strSelect); // Echo For debugging
ResultSet rset = stmt.executeQuery(strSelect);
// Step 4: Process the ResultSet by scrolling the cursor forward via next().
// For each row, retrieve the contents of the cells with getXxx(columnName).
System.out.println(“The records selected are:”);
int rowCount = 0;
while(rset.next()) { // Move the cursor to the next row
String title = rset.getString(“title”);
double price = rset.getDouble(“price”);
int qty = rset.getInt(“qty”);
System.out.println(title + “, ” + price + “, ” + qty);
++rowCount;
}
System.out.println(“Total number of records = ” + rowCount);
// Try INSERT
int returnCode = stmt.executeUpdate(
“insert into [books$] values (1002, ‘Java 101’, ‘Tan Ah Teck’, 2.2, 2)”);
System.out.println(returnCode + ” record(s) inserted.”);
// Try UPDATE
returnCode = stmt.executeUpdate(
“update [books$] set qty = qty+1 where id = 1002″);
System.out.println(returnCode + ” record(s) updated.”);
} catch(SQLException ex) {
ex.printStackTrace();
}
// Step 5: Close the resources – Done automatically by try-with-resources
}
}
LAB EXERCISE:

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