Java JDBC - Fetching a Record Example
This program gets a customer from a NorthWind-like database.
The example demonstrates the use of prepared statements, SQL SELECT * calls, and use of result meta info.
To run this example against a MySQL database you would do:
/path/to/java
-Djdbc.drivers=com.mysql.jdbc.Driver
-classpath .:mysql-connector-java-3.1.8-bin.jar
ShowCustomer
"jdbc:mysql://my.server.com:3306/Northwind?user=myuser&password=mypassword"
…
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
public class ShowCustomer {
public static void main(String[] args) {
// check for the required command-line arguments
if (args.length < 2) {
System.err.println("Usage: ShowCustomers <url> <customer-id>");
System.exit(1);
}
String url = args[0];
String customerID = args[1];
try {
// Connect to the database
Connection con = DriverManager.getConnection(url);
try {
// define the SQL query statement
String sql = "SELECT * FROM Customers WHERE CustomerID=?";
// prepare the statement
PreparedStatement stmt = con.prepareStatement(sql);
// add the customerID parameter (marked with '?')
stmt.setString(1, customerID);
// execute the SQL statement
ResultSet resultSet = stmt.executeQuery();
// if there was a result
if (resultSet.next()) {
// get the meta data describing this result
ResultSetMetaData metaData = resultSet.getMetaData();
// for each column in the result
for (int column = 1; column <= metaData.getColumnCount(); column++) {
// print the column name and value (by index)
System.out.print(metaData.getColumnName(column));
System.out.print(": ");
System.out.println(resultSet.getObject(column));
}
} else {
// customer not found
System.err.println(customerID + " not found");
}
stmt.close(); // release the statement
} finally {
con.close(); // release the connection
}
} catch (Exception e) {
e.printStackTrace(); // "handle" errors
}
}
}
