I am trying to write a program in Java that in order to work, needs to have access to a MySQL database. Below is the code for the program so far, with the I.P. address, username, and password removed for security reasons. The problem with this code is that whenever it is run, it always fails to connect to the server, even though I know that it is running and that the password that the login information is correct. My friend found a program online that checks to see if your database can be connected to, and whenever he runs it, it always outputs "Where is your MySQL JDBC Driver?" What is the MySQL JDBC driver? I am assuming that it is the cause of my problem, but I don't know that for sure. Can anyone explain this to me?
import java.sql.*;
public class main
{
public static void main(String[] args)
{
// Store the information to connect to the MySQL server in handy variables.
String url = "jdbc:mysql://(IP REMOVED FOR SAFETY):3307/";
String dbName = "attendance";
String driver = "com.mysql.jdbc.Driver";
String userName = "(USERNAME REMOVED FOR SAFETY)";
String password = "(PASSWORD REMOVED FOR SAFETY)";
// Now let's connect!
try {
Class.forName(driver).newInstance();
Connection conn = DriverManager.getConnection(url+dbName,userName,password);
} catch (Exception e) {
System.out.println("Could not connect to database!");
}
}
}
The problem could be that MySQL driver is not in your classpath.
Please look at this: http://dev.mysql.com/doc/connector-j/en/connector-j-installing-classpath.html
The MySQL JDBC driver is called MySQL Connector/J. This jar needs to be added to the classpath for your program to run.
The driver can be downloaded from: http://dev.mysql.com/downloads/connector/j/
Related
I have already installed Mysql on my computer and I have already created my database.
I have also created a Java program that connects to the database using the code attached below.
If I publish the program, will the connection to the database work correctly on other users' computers?
Will it be a problem if the code is in "localhost"?
Thanks to everyone who will help me!
public static Connection getConnection() throws Exception{
try {
String url = "jdbc:mysql://localhost:3306/mybooks?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC";
String username = "root";
String password = "mypassword";
Connection conn = DriverManager.getConnection(url, username, password);
return conn;
} catch (Exception e) {
System.out.println(e);
}
return null;
}
You will need to put a MySQL server on a machine that's accessible to all your users via a LAN or the internet. That machine will need to have a usable internet address, either a hostname like database.rich05.example.com or some IP address like 192.0.2.123.
Then you'll need to create an accounts and passwords on the MySQL server for your users. You may choose to create just one account for all your users, or a separate one for each user. (I suggest the latter approach.)
Then you'll need to change your connection string from
jdbc:mysql://localhost:3306/mybooks?whatever=val&whatever=val
to
jdbc:mysql://192.0.2.123:3306/mybooks?whatever=val&whatever=val
or
jdbc:mysql://database.rich05.example.com:3306/mybooks?whatever=val&whatever=val
or whatever the internet address is. Then you'll configure your program to use the correct usernames and passwords.
In Java programs, connection strings and usernames are often stored in properties files.
Explaining all this in detail is too much for a Stack Overflow answer. Give it a try and ask more specific questions if you need to.
I'm working on a Twitch Chat Bot which should output messages when someone types a command. The commands are getting saved in a MariaDB Database called TB. The first problem I have is that I cant connect to the Database. I saw a lot of stackoverflow posts but none of them could help me. I've never connected a database to a java program before.
My database connect method:
public void DBConnect(){
try {
String url = "jdbc:mariadb://localhost:3306/TB";
String user = "root";
String password = "";
Connection con = DriverManager.getConnection(url, user, password);
if (con != null) {
System.out.println("Connected to the database test");
}
}catch(Exception ex){
ex.printStackTrace();
}
}
I'm executing the method whenever I run my program:
public TwitchBotFenster() throws IOException, Exception {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
initComponents();
ReadServerMessages.start();
DBConnect();
}
The exception I get looks like this:
java.sql.SQLException: No suitable driver found for jdbc:mariadb://localhost:3306/TB
at java.sql.DriverManager.getConnection(DriverManager.java:689)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at main.TwitchBotFenster.DBConnect(TwitchBotFenster.java:166)
at main.TwitchBotFenster.<init>(TwitchBotFenster.java:31)
at main.Main.main(Main.java:9)
I have already downloaded the jdbc and imported it to my library. Apache and MySql are running on XAMPP.
If you're using Maven it may be fastest to shade the jdbc into your JAR. Essentially what's happening right now is that you're able to code with it because you have the dependency listed, but when you actually run your bot you're not loading the dependency.
I am getting a java.sql.SQLException: No suitable driver found. I am trying to connect to a remote database. I think I have all my credentials correct.
Here is my code
public static void main(String[] args) {
String dbUrl = "jdbc:mysql:sshhost/db1";
try {
Connection myConn = DriverManager.getConnection(dbUrl, "usr", "");
Statement myStat = myConn.createStatement();
ResultSet myRs = myStat.executeQuery("select * from students");
while (myRs.next()) {
System.out.println(myRs.getString("last_name") + ", " + myRs.getString("first_name"));
}
} catch (Exception e) {
e.printStackTrace();
}
}
The host is the same remote host that I ssh into.
I log on to mysql as root and this requires no password so I left the last parameter ""
The database I want to use while logged into root is called db1.
I'm not sure if my parameters are valid.
You have not loaded a driver. JDBC need to have a driver loaded before a connection can be made. So make sure you load an apt driver class using:
Class.forName("driverClass");
If you are using Java 6 or above(which included JDBC 4), you don't need the above mentioned dynamic driver class loading.
In both the cases, make sure the driver class you are using is present in your classpath.
You'll need to update your classpath to point to the mysql jar file. The JVM can't find a suitable mysql driver.
I'm a java beginner and I'm working on a simple application which connects to a remote mysql database using JDBC. I've tested it locally and it works just fine, however I cannot get it to work on for my remote server.
I don't think its of much use but heres the code:
Connection connection = null;
String dburl = "jdbc:mysql://314159265:3306/Db_Name";
String userName = "user";
String passWord = "password";
try {
Class.forName("com.mysql.jdbc.Driver");
connection = DriverManager.getConnection(dburl, userName, passWord);
Statement st = connection.createStatement();
String query = "INSERT INTO Example (`TestColumn`) VALUES('hello')";
int rsI = st.executeUpdate(query);
System.out.println("Hi");
}catch (Exception e) {
System.out.println(e);
} finally {
if (connection != null) {
try {
connection.close();
System.out.println("Database connection terminated");
} catch (Exception e) { /* ignore close errors */ }
}
}
When I run this, I get the following message:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
The last packet sent successfully to the server was 0 milliseconds ago.The driver has not received any packets from the server.
I'm pretty sure it must be some kind of server configuration issue.
Notes:
Username, password, IP, database name, etc. are just examples.
This could be a firewall problem, or a configuration problem. But I don't think it is a coding problem at all - you need to start troubleshooting the connection.
Trouble shoot by attempting to use third party client apps to connect to mysql. This will indicate whether it is configured for external access. Although it doesn't ensure that JDBC is visible from the outside, it does rule out some potential firewall problems.
Follow this guide to help you mess with your configurations
Remote MYSQL Database Access
If you are still stuck, it could be a coding problem so check out this page:
How to connent to a remote mysql database with java?
P.S. I am assuming you are using unix as the operating system.
I guess 314159265 could be replaced by some address....
like jdbc:mysql://localhost:3306/
or jdbc:mysql://127.0.0.1:3306/
I ve installed MySQL (last update).
I need to code, that ll create & establish a connection with SQL DB
& manage the DB(using SELECT, INSERT, CREATE).
I did everything but, I am not able to create connection. I've also installed the MySQL/J connector, I just extracted the .zip pack in a folder & added the folder path in Variables).
Can anyone tell me wat is meant by URL in the below line?
Connection connection = DriverManager.getConnection(url, username, password);
I ve tried this:
String url = "jdbc:odbc:sqlserver://localhost:3306/myfirstdb";
Connection con = DriverManager.getConnection(url, "root", "1234");
But it's not working. I am unable able to understand the term 'URL'.
Can anyone explain, the meaning of 'url' and wat should be done to connect to a SQL server from Java.
Update:
This is the Full code. It still cannot connect.
import java.sql.*;
public class TestDriver {
public static void main(String[] args) {
try {
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");//This s wat actually i did for connection
System.out.println("Driver Loaded Succesfully");
}
catch (Exception e){
System.out.println("Unable to Load Driver!!!");
}
try {
Class.forName(com.mysql.jdbc.Driver"); // initialise the driver
String url ="jdbc:mysql://localhost:3306/myfirstdb";
Connection con = DriverManager.getConnection(url, "root", "1234");
System.out.println("connection Established");
}
catch(Exception e) {
System.out.println("Couldnt get connection");
}
}
}
Can you tell me wat is the purpose of MySQL Connector/J?
In the question you seem to be using a MySQL jdbc driver with a SQL Server jdbc URL. This won't work.
If you are using a MySQL database:
Class.forName("com.mysql.jdbc.Driver"); // initialise the driver
String url ="jdbc:mysql://localhost:3306/myfirstdb";
If you are using a SQL Server database you are going to need a completely different jdbc driver. jTDS is open source and a good option. Include the jtds.jar file in your classpath and use something like:
Class.forName("net.sourceforge.jtds.jdbc.Driver"); // initialise the driver
String url = "jdbc:jtds:sqlserver://localhost:1433/myfirstdb";
Here's an extract from your code:
} catch (Exception e) {
System.out.println("Couldnt get connection");
}
You should never suppress exceptions as long as you don't understand its cause. Replace it by at least:
} catch (Exception e) {
System.out.println("Could not get connection");
e.printStackTrace();
}
Or maybe
} catch (Exception e) {
throw new RuntimeException("Could not get connection", e);
}
Either way, you should see the exception type, message and trace. In your code snippet the possible exceptions are ClassNotFoundException and SQLException. The first one would mean that the driver is not properly placed in the classpath. The second one would mean that connection cannot be obtained. The exception message and/or trace should tell in detail about the underlying root cause of the problem.
You should always observe exceptions. They tell something about the cause of the problem. You know, once a cause is understood, the solution is nothing more than obvious :)
See also:
Short MySQL/JDBC tutorial - Contains explanation about exception causes.
Further,
Can anyone tell me wat is meant by URL in the below line?
An URL is an Uniform Resource Locator. It's a common way to locate (identify) unique resources in computer systems and networks. The URL syntax for the MySQL database is explained in the documentation of the JDBC driver.
Can you tell me wat is the purpose of MySQL Connector/J?
It's the JDBC driver. The JDBC API exist of almost only interfaces. The DB vendors should provide their own concrete JDBC API implementation, which is the JDBC driver. With a JDBC driver you'll be able to connect a specific database using JDBC API.
If its MS SQL Server,
String driver = "com.microsoft.jdbc.sqlserver.SQLServerDriver";
Class.forName(driver);
String url = "jdbc:microsoft:sqlserver://host:1433/database";
Connection conn = DriverManager.getConnection(url, "username", "password");
For more info, see this to get started with Microsoft JDBC.
You can use any of the two JDBC drivers for MSSQL:
Microsoft SQL Server JDBC Driver
2.0
jTDS
For MS SQL Server driver 2.0, use
URL: jdbc:sqlserver://server:port; DatabaseName=dbname
Class name: com.microsoft.sqlserver.jdbc.SQLServerDriver
For MySql & Java, see this on SO.
You forgot a " at Class.forName(com.mysql.jdbc.Driver");
It should be
Class.forName("com.mysql.jdbc.Driver");