Randomize the multiple choice answer

[Anon]

Dear all,

I would like to write a webpage concerning the Multiple Choice questions. Each question has four answers to be chosen. In my database, there are four columns $opt1, $opt2,$opt3, $opt4, where $opt4 is the right answer. Each time, the arrangement of such four choices are randomized. Please give us the direction or code in order that the four answers are displayed with randomness.

Thanks
Simon

[[deleted]]

Whic database are you using? MySQL? postgres? informix?

[Anon]

Mysql

[[deleted]]

If you have the latest version of MySQL, (check the manual)
you can order the results by rand()

SELECT *
FROM table
WHERE bla
ORDER BY rand()

this will give your results in a random order every time.

[Anon]

Remark, in one row, there are four columns $opt1, $opt2,$opt3, $opt4, where $opt4 is the right answer. Each time, the arrangement of such four choices are
randomized.

[[deleted]]

Ah, sorry, my mistake.

This can;t be done inside the database without changing the query (a lot)
I guess the simplest would be to fetch the data from the table,
put them into an array
$aArray = array(opt1, opt2, opt3, opt4);

Then randomize the order:

shuffle($aArray);

and then print them to the screen.

[Anon]

Dear all,

The following is correct,

$sql="select * from question where questionid order by rand()";

But with error in the following

$sql="select * from question where subject like '%$subject%'and questionid order by rand()";

Please help me, thanks

Simon

[[deleted]]

And the error message was...?

[Anon]

The error message is as follow:

Warning: Supplied argument is not a valid MySQL result resource in /home/htdocs/kids/php/question/question.php on line 39

Warning: Supplied argument is not a valid MySQL result resource in /home/htdocs/kids/php/question/question.php on line 51

Please help me thanks

vincent wrote:

And the error message was...?

[Anon]

Dear all,

Under the randomization of the answer from the four choices using shuffle, I tested and found that the answer only appear the first choice or the fourth choice, but not the other two. Please give me other suggested solution.

Sincerely yours,
Simon

[[deleted]]

that means your query failed, it could not be executed by SQL.

try doing this:
if (!$result = mysql_query('select bla..'))
{
echo 'SQL error: '.mysql_error();
}
else
{
// be happy
};