php $_POST variable as column name in mysql query

Question

I have created a dropdown menu and wish to use the variable so acquired to select a column in MySQL query. I have used the following code:

<select name="selectedvalue">
    <option value="n1">Birthweight</option>
    <option value="n2">3-month weight</option>
    <option value="n3">6-month weight</option>

</select>

Later I am retrieving the variable using

$selval = ($_POST['selectedvalue']);

MySQL query:

$lambings = "Select year, `".($_POST['selectedvalue'])."` as weight from mytable 
      GROUP by year(dob)";

but the sql query fails every time.

print what is inside your $selval or $_POST['selectedvalue']? — A l w a y s S u n n y
– A l w a y s S u n n y, Commented Oct 20, 2018 at 13:46
If you print($lambings);exit; and copy/paste the query does it run via phpMyAdmin or mysql-workbench, etc. ? — ivanivan
– ivanivan, Commented Oct 20, 2018 at 13:48
Do you execute $lambings? What driver are you using? This is open to SQL injections. — user3783243
– user3783243, Commented Oct 20, 2018 at 13:48

Prasinus Albus · Accepted Answer · 2018-10-20 13:58:34Z

1

The problem is not the variable, but the query itself. You can use group by only when you have count/ averages etc in your query.

either change that or remove the group by part in your query.

answered Oct 20, 2018 at 13:58

Prasinus Albus

4161 gold badge3 silver badges21 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Rachel Watson Over a year ago

Yes that was it! Thanks very much

Collectives™ on Stack Overflow

php $_POST variable as column name in mysql query

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related