fiercearyan / LearnJDBC

LearnJDBC

Steps to Connect with Database

1. Load the driver
  We can only use the driver after loading it on our machine.

  1st Method
    Class.forName("Driver_name")
    e.g. Class.forName("com.mysql.jdbc.Driver")

  2nd Method
    DriverManager.registerDriver(new com.mysql.cj.jdbc.Driver())

2. Create a connection Connection gets established between program and database

   import java.sql.*; Connection conn = DriverManager.getConnection("url","username","password"); e.g. ("jdbc:mysql://localhost:3306/jdbctest","root","password")

3. Create a query We will fire SQL queries after establishing connection. We will need one of three things below: a. Statement - If we need simple query. b. PreparedStatement - If we have question marks/complex query. c. CallableStatement - If we need functions/procedures from database.

   a. Statement Example
   

   String q = " select * from students" ; Statement stmt = conn.createstatement(); § stmt.executeQuery() - when we expect only data e.g. ResultSet set = stmt.executeQuery(); It will pull all data in set. § stmt.executeUpdate() - when we expect update and not data § stmt.execute();

4. Process the data We will process our data with help of set. We have methods for it.

   set.next() - If there is next row available? set.getInt() set.getString() e.g. while(set.next()){ int id = set.getInt(ColumnNumber/"ColumnName"); String name = set.getString(ColumnNumber/"ColumnName"); System.out.println(id + " " + name); }

5.Close the connection conn.close();