Cannot connect to Mysql database using Java

Question

I am running the following code on a Windows Server box using Java on Eclipse.

Connection conn = null; // connection object  
Statement stmt = null; // statement object  
ResultSet rs = null; // result set object  
try{  
  Class.forName("com.mysql.jdbc.Driver").newInstance();  
  conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/errorcodes", "myusername", "mypassword");   
  System.out.println ("Database connection established");  
 }catch (Exception e){  
  System.err.println ("Cannot connect to database server");  
}

And i keep seeing the "Cannot connect to database server error". Any ideas what i might be doing wrong?
I have tried netstat -an and i see : TCP 127.0.0.1:4464 127.0.0.1:3306 Established

Can you print out a stack trace of the exception? Replace "System.err.println(...)" with e.printStackTrace(); — Todd
– Todd, Commented Jun 18, 2011 at 4:44
Are you sure the password and login are correct and can see that DB? — JohnFx
– JohnFx, Commented Jun 18, 2011 at 4:47
Try putting the Class.forName statement and the DriverManager.getConnection statement in different try clauses, to see if you're able to load the Driver. — bbg
– bbg, Commented Jun 18, 2011 at 4:50
I added the e.printStackTrace. And added the connector jar. Now I see: Cannot connect to database server java.sql.SQLException: Access denied for user 'myusername'@'localhost' (using password: NO) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073) and so on. How do i cross check my sql username? I know my password is correct. And why does it say "using password: NO) ? — stumped
– stumped, Commented Jun 18, 2011 at 5:05

Bohemian · Accepted Answer · 2011-06-18 04:50:56Z

2

My guess? You haven't got the mysql jdbc connector jar in your classpath. It should be called something like mysql-connector-java-5.1.16-bin.jar, depending on your version of mysql

If you don't have that jar, visit here

answered Jun 18, 2011 at 4:50

Bohemian♦

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2 Comments

stumped Over a year ago

Thanks, I just did this and added to jar to my project. Now I see: Cannot connect to database server java.sql.SQLException: Access denied for user 'myusername'@'localhost' (using password: NO) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073) and so on.

ahmet alp balkan Over a year ago

Then your database credentials or access privileges are incorrect if database server is running. Don't catch all exceptions, or elaborate them with more than one catch blocks.

Askar Kalykov · Accepted Answer · 2011-06-18 04:54:45Z

0

Do you sure that it is mysql running on port 3306 and that it's version is supported by your connector/j?

answered Jun 18, 2011 at 4:54

Askar Kalykov

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1 Comment

stumped Over a year ago

I am running MySQL 5.5 and my connector is 5.1.16. Both are the latest.

prasad.gai · Accepted Answer · 2011-06-18 05:46:00Z

0

i think you did not start the MySql server in your PC.before running your application

answered Jun 18, 2011 at 5:46

prasad.gai

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Comments

John · Accepted Answer · 2011-06-18 06:46:07Z

0

Try the followings:

Clean and rebuild the project in eclipse.
Try to access the mysql database using the username and password in command prompt to ensure the username and password are correct.

If you want to ensure the username and password , you have to query the user table in mysql table again to need another mysql admin account to query.

answered Jun 18, 2011 at 6:46

John

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waleed_Alrasheed · Accepted Answer · 2013-09-29 11:26:02Z

0

It is simple .. you need .jar file called mysql-connector-java-5.1.16-bin.jar ,,, download it and add it to your libs ...

good luck !!!

answered Sep 29, 2013 at 11:26

waleed_Alrasheed

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