Java Web App - cannot edit database despite the connection works

I'm creating java web application using maven. I added mySQL local database as a datasource and when I'm testing connection everything is ok however when I start the app and try to add a new record it doesn't work, I mean code is executing and app is working but there is no new data in database. I also cannot check if there is some data in database. There is no error or anything but other instructions not conneted to database work properly. In my web.xml I've got

<resource-ref>
    <res-ref-name>jdbc/DSTestPool</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
</resource-ref> 

In jetty.xml

<New id="DSTestPool" class="org.eclipse.jetty.plus.jndi.Resource">
        <Arg></Arg>
        <Arg>jdbc/DSTestPool</Arg>
        <Arg>
            <New class="org.apache.commons.dbcp2.BasicDataSource">
                <Set name="driverClassName">com.mysql.jdbc.Driver</Set>
                <Set name="url">jdbc:mysql://localhost:3306/psi3</Set>
                <Set name="username">root</Set>
                <Set name="password"></Set>
                <Set name="maxTotal">100</Set>
                <Set name="maxIdle">30</Set>
                <Set name="minIdle">10</Set>
            </New>
        </Arg>
    </New>

and I'm creating user like this

public class UsersDAO {
    private DataSource ds;
    public UsersDAO(DataSource ds) {
        this.ds = ds;
    }
    public void createUser(User user){
        Connection con = null;
        PreparedStatement pst = null;
        try {
            con = ds.getConnection("root","");
            String sql="insert into users (Username,Password,Valid) values(?,?,?)";
            pst = con.prepareStatement(sql);
            pst.setString(1, user.getLogin());
            pst.setString(2, user.getPassMD5());
            pst.setInt(3,1);
            pst.executeUpdate();
        } catch (Exception e) {
            System.out.println(e);
        } finally {
            DbTools.closeQuietly(pst, con);
        }
    }
}

my datasources.xml looks like this

<?xml version="1.0" encoding="UTF-8"?>
<project version="4">
  <component name="DataSourceManagerImpl" format="xml" hash="4078573267">
    <data-source source="LOCAL" name="MySQL - psi3@localhost" uuid="c2a621c7-089c-4d40-9767-1387f9bfb343">
      <driver-ref>mysql</driver-ref>
      <synchronize>true</synchronize>
      <jdbc-driver>com.mysql.jdbc.Driver</jdbc-driver>
      <jdbc-url>jdbc:mysql://localhost:3306/psi3</jdbc-url>
      <driver-properties>
        <property name="zeroDateTimeBehavior" value="convertToNull" />
        <property name="tinyInt1isBit" value="false" />
        <property name="characterEncoding" value="utf8" />
        <property name="characterSetResults" value="utf8" />
        <property name="yearIsDateType" value="false" />
      </driver-properties>
      <libraries />
    </data-source>
  </component>
</project>

I've tried a few things but nothing seems to work, test shows that connection is ok and I do not know what to do with that. I wrote some apps in java but it's my first time with java web and I have no idea what to do with that so I will be grateful if someone can help me. I'm using IntelliJ IDEA 14.0.3.