com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException

Error is:

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'book_id = 'DSP123'' at line 1 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27) at java.lang.reflect.Constructor.newInstance(Constructor.java:513) at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) at com.mysql.jdbc.Util.getInstance(Util.java:386) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1052) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3609) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3541) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2002) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2163) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2624) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2127) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2427) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2345) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2330) at Frames.Books.jButton2ActionPerformed(Books.java:424) at Frames.Books.access$300(Books.java:26) at Frames.Books$4.actionPerformed(Books.java:181) at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1995) at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2318) at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:387) at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:242) at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:236) at java.awt.Component.processMouseEvent(Component.java:6263) at javax.swing.JComponent.processMouseEvent(JComponent.java:3267) at java.awt.Component.processEvent(Component.java:6028) at java.awt.Container.processEvent(Container.java:2041) at java.awt.Component.dispatchEventImpl(Component.java:4630) at java.awt.Container.dispatchEventImpl(Container.java:2099) at java.awt.Component.dispatchEvent(Component.java:4460) at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4574) at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4238) at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4168) at java.awt.Container.dispatchEventImpl(Container.java:2085) at java.awt.Window.dispatchEventImpl(Window.java:2478) at java.awt.Component.dispatchEvent(Component.java:4460) at java.awt.EventQueue.dispatchEvent(EventQueue.java:599) at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269) at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184) at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169) at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161) at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Code is:

private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
    String bookid = jTextField2.getText();
    String doi = "";
    Calendar cal = new GregorianCalendar();
    doi = doi + cal.get(Calendar.YEAR) + "-" + cal.get(Calendar.MONTH) + "-" + cal.get(Calendar.DAY_OF_MONTH);
    String sql = "insert into library.issue values ('"+ bookid + "','librarian','"+ username + "','" + doi + "')";
    try
    {
        int i = st.executeUpdate(sql);
        if(i>0)
           JOptionPane.showMessageDialog(null,"BOOK IS ISSUED","SUCCESS",JOptionPane.PLAIN_MESSAGE);
        else
           JOptionPane.showMessageDialog(null,"problem in issuing book","FAILURE",JOptionPane.ERROR_MESSAGE);
        bookid = bookid.toUpperCase();
        String sql1 = "update library.books set status = " + 1 + "where book_id = '" + bookid + "'";
        PreparedStatement pstmt=c.prepareStatement(sql1);
        int j= pstmt.executeUpdate() ;
        //int j = st.executeUpdate(sql1);
    }
    catch(Exception ex)
    {
        ex.printStackTrace();
    }
}