Java has its own API which JDBC API which uses JDBC drivers for database connections. JDBC API provides the applications-to-JDBC connection and JDBC driver provides a manager-to-driver connection. Following are the 5 important steps to connect java application to our database using JDBC.
- Registering the Java class
- Creating a Connection
- Creating a Statement
- Executing queries
- Closing connection
Note: Load mysqlconnector.jar into your program.
Steps:
- Download MySQLConnect/J (JDBC connector jar file) from the following link https://dev.mysql.com/downloads/connector/j
- Select platform-independent in select OS option
- Copy mysql-connector-java-5.1.34-bin.jar file in your project
- Right-click on it , select Build Path-> Configure Build path -> libraries -> Add JARS
- In JAR selection window, select mysql-connector-java-5.1.34-bin.jar library under your project
- Click OK
- Create a Database, add a table with records using MySQL cmd.
Java
// Update a Column in a Table // dont forget to import below packageimport java.sql.*; public class Database { // url that points to mysql database, 'db' is database // name static final String url public static void main(String[] args) throws ClassNotFoundException { try { // this Class.forName() method is user for // driver registration with name of the driver // as argument i have used MySQL driver Class.forName("com.mysql.jdbc.Driver"); // getConnection() establishes a connection. It // takes url that points to your database, // username and password of MySQL connections as // arguments Connection conn = DriverManager.getConnection( url, "root", "1234"); // create.Statement() creates statement object // which is responsible for executing queries on // table Statement stmt = conn.createStatement(); // Executing the query, student is the table // name and RollNo is the new column String query = "ALTER TABLE student RENAME COLUMN roll_no TO RollNo"; // executeUpdate() is used for INSERT, UPDATE, // DELETE statements.It returns number of rows // affected by the execution of the statement int result = stmt.executeUpdate(query); // if result is greater than 0, it means values // has been added if (result > 0) System.out.println( "table successfully updated."); else System.out.println("unable to update"); // closing connection conn.close(); } catch (SQLException e) { System.out.println(e); } }} |
