将列表框选项值保存到mysql中，然后再次显示php mysql

Question

I want to save list option values into MySQL then again want to display them as a list.

I need that for a dynamic query.

 <select multiple id="to" size="15" name="to[]">
    <option value="a">a</option>
    <option value="b">b</option>
    <option value="c">c</option>
    <option value="d">d</option>
 </select>

This is php code to change it into (a,b,c,d):

   $joinedString = array();
   $var1 = $_POST['to'];
   $joinedString = implode(',', $var1);
   $joinedString;

I just change this into a,b,c,d with implode function, and its working fine.

But don't know how to save it in mysql and how to again fetch data from database and make this as:

 <select multiple id="to" size="15" name="to[]">
    <option value="a">a</option>
    <option value="b">b</option>
    <option value="c">c</option>
    <option value="d">d</option>
</select>

Answer 1

Now that you have the string a,b,c,d in variable $joinedString , Just use it to insert into your database. Remember you need to insert this string like this 'a,b,c,d' and not simply a,b,c,d. So, first format your string in inverted commas like 'a,b,c,d'. Now, that you have done it, just use insert command.

Insert into Table_name set column_name='".$joinedString."' where some_condition. 

After that, you retrieve it if you have to use it again, using "Select" query.

Select column_name from Table_name where Some_condition

It would give you your variable back to you in format, 'a,b,c,d'. Save it in some variable $variable. Now you use explode function to make an array of this string using comma.

$arr_string  = explode(",",$variable);
This $arr_string would be an array like this 

array(0=> a,
      1=> b,
      2=> c,
      3=> d)

Now you loop over this array using foreach and make the select option.

<select multiple id="to" size="15" name="to[]">
<?php 
     foreach($variable as $key=>$val)
     {
       echo "<option value='".$val."'>".$val."</option>";
     }
?>
</select>

Answer 2

If you are storing comma separated value within database you can get the value from database using query and from result you can simply implement that within your file using explode function of PHP as :

<?php
$joinedString = 'a,b,c,d'; // fetched data from database using query if you are storing data within database comma separated
$data = explode(',',$joinedString);
?>
<select multiple id="to" size="15" name="to[]">
    <?php foreach($data as $key => $value){?>
    <option value="<?php echo $value; ?>"><?php echo $value; ?></option>
    <?php } ?>
</select>

I think this might be the expected answer..