CODEWITHSUNDEEP
javamysql
samira
samira

Reputation: 1295

connecting to mysql with java

i have written my first program but in output i cant see any thing. i create my table in mysql.

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.Statement; 


public class tester {

    public tester() {
    }
   public static void main(String[] args)  {


    String driver = "com.mysql.jdbc.Driver"; 
    String user = "root"; 
    String pass = "123456"; 

    Connection connection = null; 
    Statement statement = null; 
    ResultSet resultSet = null; 
ResultSet rs;
    try { 
     Class.forName(driver).newInstance(); 
     connection = DriverManager.getConnection( 
        "jdbc:mysql://./test", user, pass); 
     statement = connection.createStatement(); 
     resultSet = statement.executeQuery("SELECT * FROM  student"); 
     rs = statement.getResultSet();
        while (rs.next()) {            
           System.out.print(rs.getString("sname")+("\t")) ;
           System.out.print(rs.getString("sfamily")+("\t")) ;
           System.out.print(rs.getString("saddress")+("\t")) ;
        }
     rs.close();
     statement.close();
     connection.close();

    } catch (Exception e) { 
}
   }
}

in my output i have: run: BUILD SUCCESSFUL (total time: 0 seconds) i cant see my records. what shall i do? i add mysql-connector-java-5.1.18 in my project.

Upvotes: 0

Views: 188

Answers (5)

Suresh
Suresh

Reputation: 1504

1.You dont need two resultset.You can go below code.

import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.Statement; 

//</editor-fold>
/**
 *
 * @author mohsen
 */
public class tester {

    public tester() {
    }
   public static void main(String[] args)  {


    String driver = "com.mysql.jdbc.Driver"; 
    String user = "root"; 
    String pass = "123456"; 
    String dbUrl ="jdbc:mysql://localhost:3306/test1";

    Connection connection = null; 
    Statement statement = null; 
   /* ResultSet resultSet = null; */
ResultSet rs =null;
    try { 
     Class.forName(driver).newInstance(); 
     connection = DriverManager.getConnection(dbUrl, user, pass); 
     statement = connection.createStatement(); 
     rs = statement.executeQuery("SELECT * FROM  student"); 
   //  rs = statement.getResultSet();
        while (rs.next()) {            
           System.out.print(rs.getString("sname")+("\t")) ;
           System.out.print(rs.getString("sfamily")+("\t")) ;
           System.out.print(rs.getString("saddress")+("\t")) ;
        }
     rs.close();
     statement.close();
     connection.close();

    } catch (Exception e) { 

}
   }

}

2.Try to print Exception.So you got what is error in that.

3.Always close connection in finally.

Upvotes: 0

gprathour
gprathour

Reputation: 15333

Try with the following code

 Class.forName("com.mysql.jdbc.Driver");
 connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/test",user,pass);
 statement = connection.createStatement();
 resultSet = statement.executeQuery("SELECT * FROM  student");
 while (resultSet.next()) {
        System.out.print(resultSet.getString("sname")+("\t")) ;
        System.out.print(resultSet.getString("sfamily")+("\t")) ;
        System.out.print(resultSet.getString("saddress")+("\t")) ;
 }

And ADD THIS to catch block

catch (Exception e) { 
      e.printStackTrace();
}

That's why you are not getting any exception.

Suggestions

  1. You don't need two different result sets. You can do this way too :

    resultSet = statement.executeQuery("SELECT * FROM  student");
while (resultSet.next()) {
   System.out.print(resultSet.getString("sname")+("\t")) ;
   System.out.print(resultSet.getString("sfamily")+("\t")) ;
   System.out.print(resultSet.getString("saddress")+("\t")) ;
}

  2. Close the connection, result set etc. in finally block.

  3. Your class name should be Tester according to Java Naming Conventions.

Upvotes: 0

Dawood
Dawood

Reputation: 5306

First of all, you're not getting any exceptions because you're not printing them. Change this part:

} catch (Exception e) { 
}

to this:

} catch (Exception e) { 
    e.printStackTrace();
}

I suspect the problem would be with the connection string here:

connection = DriverManager.getConnection("jdbc:mysql://./test", user, pass);

Upvotes: 1

A N M Bazlur Rahman
A N M Bazlur Rahman

Reputation: 2300

hey I think this code works. 

public static void main(String[] args) {

    String driver = "com.mysql.jdbc.Driver";
    String user = "root";
    String pass = "";

    Connection connection = null;
    Statement statement = null;
    ResultSet rs = null;

    try {
        Class.forName(driver).newInstance();
        connection = DriverManager.getConnection(
                "jdbc:mysql://localhost/ums1", user, pass);
        statement = connection.createStatement();
        rs = statement.executeQuery("SELECT * FROM user");

        while (rs.next()) {
            System.out.print(rs.getString(1) + ("\t"));
            System.out.print(rs.getString(2) + ("\t"));
            System.out.print(rs.getString(3) + ("\t"));
        }

    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            connection.close();
            rs.close();
            statement.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

mind to change database url and table name. I tested with my one.

Upvotes: 0

naresh
naresh

Reputation: 2113

Are you using some IDE like eclipse? Else, compile and run the program as following:

javac tester.java
java tester

And in your catch clause do the following, instead of completely ignoring the exception:

catch (Exception e){
e.printStackTrace();
}

Upvotes: 0

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