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Accessing Database using Java and JDBC

                         

Accessing Database using Java and JDBC

Database plays an important role in storing large amount of data in a pattern. Here we are going develop and example to access the database using Java and JDBC. For this, firstly we need to establish a connection between database and java file with the help of various types of APIs, interfaces and methods. We are using MySQL database.

Connection: This  interface specifies connection with specific databases like: MySQL, Ms-Access, Oracle etc and java files. The SQL statements are executed within the context of this interface.

Class.forName(String driver): It loads the driver.

DriverManager: This class controls a set of JDBC drivers. Each driver has to be register with this class.

getConnection(String url, String userName, String password): This method establishes a connection to specified database url. It is having three arguments:
        url: - Database url where stored or created your database
        username: - User name of MySQL
        password: -Password of MySQL 

getMetaData(): This is a method of Connection interface. It retrieves the metadata of the database.

DataBaseMetaData: This interface gives information about the database like number of tables in the database, columns of the table etc.

getTables(null, null, "%", null): This method provides the description of the tables available in the given catalog. As we have set other parameters null, so it will provide only table names.

Here is the code:

import java.sql.*;

public class AccessDatabases {
  public static void main(String[] args) {
    try {
      Class.forName("com.mysql.jdbc.Driver").newInstance();
      Connection con = DriverManager.getConnection(
          "jdbc:mysql://localhost:3306/test""root""root");
      Statement st = con.createStatement();
      DatabaseMetaData meta = con.getMetaData();
      ResultSet rs = meta.getTables(null, null, "%"null);
      String tableNames = "";
      while (rs.next()) {
        tableNames = rs.getString(3);
        System.out.println(tableNames);
      }
    catch (Exception e) {
    }
  }
}

In this section we studies how to connect to database and then list all the tables in the database. We have used MySQL database server.

                         

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