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Why is my JDBC connection only failing when deployed through Jetty?

To pretense, i'm new to web development. I have a java web application that is deployed through Jetty, and I have an issue that is really confusing me. In order to display data from my database in the web app I must establish a database connection, which I can do when I am unit testing my code, but when I call the same methods from .jsp pages to populate the web app I get a message telling me this:
java.sql.SQLException: No suitable driver found for jdbc:sqlserver://localhost:1433;integratedSecurity=true;database=TicketITBookingSystemDatabase;loginTimeout=30;
Here is the rest of the relevant code:
public void queryDatabase(String query){
ResultSet resultSet = null;
String connectionUrl = establishDatabaseConnection();
try (Connection connection = DriverManager.getConnection(connectionUrl);
Statement statement = connection.createStatement();) {
//Execute the sql statement passed as the query parameter.
resultSet = statement.executeQuery(query);
processResultSet(resultSet);
statement.close();
}
// Handle any errors that may have occurred.
catch (SQLException e) {
e.printStackTrace(); //why is this being hit but only on the web build
}
And the event that is being called:
public List<String[]> getAllEvents(){
queryDatabase("EXEC dbo.sp_GetAllEventDetails");
return events;
}
Thanks.

You have to add the driver of the database on the classpath of Jetty.
Check if it is present or not.

The problem is that either you did not add the driver jar to the classpath of Jetty, or - if you deployed it with the application - you need to load the driver explicitly with Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"). JDBC automatic driver loading only works when the driver is on the initial classpath, not if it is on a context classpath.
However, it is generally inadvisable to use DriverManager directly from a web application. The use of a DataSource is usually better, especially if the data source implementation provides a connection pool.

sybase java DB connection issue

I want to create sybase DB connection in java application.
I've added jconn4.jar to my project, but when I'm connecting to DB in code I have exception ClassNotFoundException: com.sybase.jdbc4.jdbc.SybDriver.
My connection:
SqlConnect() {
try {
DriverManager.registerDriver(new com.sybase.jdbc4.jdbc.SybDriver());
} catch (SQLException e) {
System.err.println("SQL exception " + e.getMessage());
}
}
And also
public void connect() {
try {
connection = DriverManager.getConnection("jdbc:sybase:Tds:localhost:5000", "DBA", "sql");
connection.setAutoCommit(false);
} catch (SQLException e) {
}
}
I want to connect to demo PowerBuilder database, with params:
DSN=EAS Demo DB V125;UID=dba;PWD=sql
What I'm doing wrong?
ADDED
Also when I'm trying to create database connection via intelij database work plugin i also have the same error.

Make sure you have respected jars included on your classpath.
The following works for me:
Use Class.forname to load the drivers
Recommended Approach:
Class.forName("sybase.jdbc.sqlanywhere.IDriver")
con = DriverManager.getConnection("jdbc:sqlanywhere:uid=DBA;pwd=sql");
Another way around:
DriverManager.registerDriver((Driver) Class.forName("sybase.jdbc.sqlanywhere.IDriver").newInstance());
con = DriverManager.getConnection("jdbc:sqlanywhere:uid=DBA;pwd=sql");
The following link will help you in installing drivers:
How to connect Sybase database using Java code in NetBeans?

So, the other jdbc type driver resoled my problem - I connected sajdbcX driver and changed connection string:
connection = DriverManager.getConnection("jdbc:sqlanywhere:uid=DBA;pwd=sql");
So, also thanx Mark Rotteveel for advice - I removed driver register code as redurdrant.
And thank all for ideas.

How to check if another instance of Derby is already booted?

I'm writing some Java application that uses Java DB (i.e. Apache Derby) as database. I use the following method to connect to database:
Connection getConnection() throws SQLException {
EmbeddedDataSource ds = new EmbeddedDataSource();
ds.setDatabaseName(dbUri);
ds.setPassword(password);
ds.setUser(username);
Connection conn = ds.getConnection();
conn.setSchema(schema);
return conn;
}
This works ok, but sometimes I get the following exception:
java.sql.SQLException: Another instance of Derby may have already booted the database
This happens when I run my application and at the same time SQuirreL SQL Client is connected to my database. So everything works as expected, but I would like to be able to check for this in my getConnection() method. I other words, I would like to check if any sessions are opened to my database, and for example, close them, throw my own exception or display error dialog box. I don't know how to do this.
Thx

Rather than declaring that your application "throws SQLException", you can use a "try" block to catch the SQLException, then examine the exception and decide if it is the "Another instance of Derby" exception or not.
Then, you can throw your own exception from your "getConnection" method accordingly.

I modified my getConnection() method to something like below. It does what i want:
Connection getConnection() throws SQLException, DAOConnection {
EmbeddedDataSource ds = new EmbeddedDataSource();
ds.setDatabaseName(dbUri);
ds.setPassword(password);
ds.setUser(username);
Connection conn = null;
try {
conn = ds.getConnection();
} catch (SQLException e) {
// check if cannot connect due to "Another instance of
// Derby may have already booted the database".
// The error code of this exception is 45000.
if (e.getNextException().getErrorCode() == 45000) {
throw new DAOConnection(e.getNextException().getMessage());
}
throw new SQLException(e);
}
conn.setSchema(schema);
return conn;
}

Prevention is better than cure. IMO, catching exception and then realizing it was duplicate Derby server started is not an ideal design. Better would be to prevent duplicate instantiation. If possible you can synchronize your getConnection() method or make it part of a singleton class or load the embedded Derby driver from static initializer block of a startup/main class which is loaded only once by JVM and hence Derby will be started only once. Something like following in the main/startup class should do the trick:
static {
try {
Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
}
catch(Exception e){
.....
}
}
Per the link here http://db.apache.org/derby/docs/10.3/devguide/tdevdvlp38381.html loading the Driver should start the Derby embedded system.

How to connect MySQL to Java program

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");

JDBC Connection Issue

I have create a getDBConnection method in my Java application. This returns a connection object, and hence I haven't closed this connection in this method itself.
Now, I am invoking this method from various methods in my application at regular intervals, and closing them inside a try - finally block. I thought this should free up the connection after use. However, I am seeing a large number of connections opened (about 50) in the MySQL Administrator's Server Connections tab.
//Defining a method to retrieve a database connection
// PropDemo is a properties class that retrieves Database related values from a file
public Connection getDBConnection() {
//Instantiating the Properties object
PropDemo prop = new PropDemo();
Connection con = null;
// Retrieving values from the parameters.properties file
String JdbcDriver = prop.getMessage("JdbcDriver");
String JdbcUrlPrefix = prop.getMessage("JdbcUrlPrefix");
String DBIP = prop.getMessage("DBIP");
String DBName = prop.getMessage("DBName");
String DBUser = prop.getMessage("DBUser");
String DBPassword = prop.getMessage("DBPassword");
try {
// Loading and instantiating the JDBC MySQL connector driver class
Class.forName(JdbcDriver).newInstance();
con = DriverManager.getConnection(JdbcUrlPrefix + DBIP + "/" + DBName, DBUser, DBPassword);
if (con.isClosed())
Logger.log("Connection cannot be established", "vm");
} catch (Exception e) {
Logger.log("Exception: " + e, "vm");
Logger.log(Logger.stack2string(e), "vm");
}
return con;
}
I am also closing the associated ResultSet and Statement Objects. What could be missing here?
I am planning to replace all the Statements with PreparedStatements for efficiency and security reasons. Will that help significantly? What else can be done?
EDIT:
This is just a core java application that is repeatedly quering for changes in some fields in a MySQL database through MySQL-JDBC connector. I am not using any framework like Spring or Hibernate.

Your code looks sane.
That's how you're creating a new connection.
Probably the error is where you close it.
You should close it in a finally block.
Some additional questions.
1) Are you sure those 50 conections come from this program ? Maybe there are some others comming from your same office. To confirm this you would need to stop the program, and look again in your connection monitor.
2) Does your application uses many connection simultaneously? Probably its a peak when you're using 50 at the same time.
If you can post the code where you close the connection. Chances are the problem is there.
Additionally I would suggest you to use a connection pool. You can build one your self or you can see the results from this page:
How many JDBC connections in Java?

Are you closing the connection object when you application closes as well?

Are you using your JDBC connection within a J2EE application server or with Hibernate?
Both of these tend to start out with a fairly high connection pool to begin with, so you would see a large number.
Check out the details on connection pooling.

You could take a Singleton approach to the problem and only create a new Connection object if the current one is null:
If (connectionObject != null){
return connectionObject;
}else {
//create new connection object
}
This will make sure that you only have one non-null connection at any time.