如何使用表单标签将数据发送到数据库？

I can send data to database but using tag. I want to use tag so that the validation in my page will show like "please enter a valid email-address", "password do not match" and many more.

The problem is when I use tag it shows no validation but the data send to db. But if use tag it shows the validation, but the data is not entering into db.

Here is the view code:

<div class="form-horizontal" id="block-validate">
    <?php echo form_open(base_url("index.php/main/editClass"));?>
    <div class="form-group">
        <label class="control-label col-lg-2"><b>
            Course Code-Section
            </b></label>
        <div class="col-lg-4">
            <input class="form-control" name="ccs" type="text" value="<?php echo $Course_Code_Section;?>">
        </div>
    </div>
    <div class="form-group">
        <label class="control-label col-lg-2"><b>
            Course Description
            </b></label>
        <div class="col-lg-4">
            <input class="form-control" name="des" type="text" value="<?php echo $Description;?>">
        </div>
    </div>
    <div class="form-group">
        <label class="control-label col-lg-2"><b>
            School Year-Semester
            </b></label>
        <div class="col-lg-4">
            <input class="form-control" name="sys" type="text" value="<?php echo $School_Year_Semester;?>">
        </div>
    </div>
    <div class="form-group">
        <label class="control-label col-lg-2"><b>
            Room
            </b></label>
        <div class="col-lg-4">
            <input class="form-control" name="rm" type="text" value="<?php echo $Room;?>">
        </div>
    </div>
    <div class="form-group">
        <label class="control-label col-lg-2"><b>
            Day-Time
            </b></label>
        <div class="col-lg-4">
            <input class="form-control" name="dt" type="text" value="<?php echo $Day_Time;?>">
        </div>
    </div>
    <div class="form-group">
        <label class="control-label col-lg-2"><b>
            Student
            </b></label>
        <div class="col-lg-4">
            <input class="form-control" name="stu" type="text" value="<?php echo $Student;?>">
        </div>
    </div>
    <div class="form-actions">
        <input type="hidden" name="id" value="<?php echo $CID;?>">
        <label class="control-label col-lg-2"></label>
        <button type="submit" class="btn btn-primary btn-grad btn-rect">Submit</button>
        <a href ="<?php echo base_url();?>index.php/main/index"class="btn btn-default btn-grad btn-rect">Cancel</a>
    </div>
    <?php echo form_close();?>
</div> 

Here is the code that I am changing:

<div class="form-horizontal" id="block-validate">

And I changed it to:

<form class="form-horizontal" id="block-validate">

When I use the form tag, the url shows this:

http://localhost/ams/index.php/main/showEditClassView?ccs=CPE+506-CPE42FA1&des=Software+Engineering&sys=SY+2016-2017+2nd+Sem&rm=A-225&dt=Saturday-07%3A30+AM-12%3A30+PM&stu=Ronnel+Gonzales&id=1