SQL ASC or DESC display order by change of records by column head title of a field

Click the Mark header to change the display order.

Name	mark
Alex John	55
Big John	55
Krish Star	60
John Mike	60
Babby John	69
John Deo	75
Tade Row	88
Gimmy	88
Marry Toeey	88

Read how order by is used in php paging script.
We can reverse the display order or change field on which the order of display is applied by managing the order by sql query. Here the option ( link ) is available to user to change the order of display as per their requirement.
We will be using PHP script in managing or changing the query as per the user clicks on the column header hyper link of the field.

We can write our query to display the records in the order of marks obtained by the students from highest to lowest.

Here is the php code

if(isset($by) and $by=="asc"){
$by="desc"; // Order is set to decreasing 
}else{
$by="asc";  // Order is set to increasing 
}

$query="SELECT * FROM `student` where class='Four' ORDER BY mark $by ";
$rt=mysql_query($query);
echo "<table border='0' width='300' cellspacing='0' cellpadding='0' align=center>";
echo "<tr><td><b>Name</b></td>
<td><b><a href='sql_order-change.php?by=$by'>mark</a></b></td></tr>";

while ( $nt=mysql_fetch_array($rt)){
echo "<tr><td>$nt[name]</td><td>$nt[mark]</td></tr>";
}

echo "</table>";

Note that the value of $by we are setting before the query by an if - else logical condition and when ever user clicks the header link of the mark table the value of $by changes and the order by query also changes. The value of $by gets either 'asc' or 'desc'.
ORDER BY query

Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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Erkki	15-03-2014
How do you get rid of double or triple and so on "by=asc" "by=desc" lines on url line in the browser? Whenever you implement it in your own code the url line just generates more variables "by=asc&by=desc" an so on.

phraglets	03-02-2015
do you have a sample of dynamic table that can display all the table in the database even if their field are different, with pagination

smo	06-02-2015
You can download the plus admin script . Or check this page to list tables

Query to change the display order of records on a field dynamically

Subhendu Mohapatra