Dynamically creating OR conditions by passing an array to a query in MySQL PHP

Question

I am trying to create OR condition dynamically using an array. Given an array, of course names $courses = array('Eng, 'Deu', 'Bio', 'Chemi') I want to have a SQL query that uses the values of the array in its AND clause with OR conditions like:

    SELECT *
        FROM classe
        /* The OR conditions should be created in AND clause using array */
        WHERE class = 'EFG' AND (course = 'Eng' OR course = 'Deu' OR course = 'Bio')

I trying to do it in PHP MySQL.

Any help would be really appreciated.

Thanks in Advance.

Maybe `and course in( 'Eng', 'Deu', 'Bio')`... should be able to generate that pretty easily with `implode`...or if using PDO this can be much easier. — user3783243, Nov 20 '18 at 20:04
@user3783243 Be very careful using `implode` on user data as that's an express train to [SQL injection bugs](http://bobby-tables.com/). — tadman, Nov 20 '18 at 20:42

score 2 · Accepted Answer · answered Nov 20 '18 at 20:04

2

Instead of so many OR clauses, you can simply use IN(..):

SELECT *
FROM classe
WHERE class = 'EFG' AND course IN ('Eng' ,'Deu', 'Bio')

In the PHP code, you can use implode() function to convert the array into a comma separated string, and use it in the query string generation.

answered Nov 20 '18 at 20:04

Madhur Bhaiya

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Thanks for your reply, with implode I am getting a string like this: "Eng , Deu, Bio" and I want the values like this: " 'Eng' ,'Deu', 'Bio' " – Musayyab Naveed Nov 20 '18 at 20:30
@MusayyabNaveed your problem statement says that you get an array. Please confirm what exactly are you getting ? – Madhur Bhaiya Nov 20 '18 at 20:32
yes it in array: $courses = array('Rel-GK1', 'F6', 'Bio', 'Chemi'); $placeholders = implode(', ', $courses); – Musayyab Naveed Nov 20 '18 at 20:33
@MusayyabNaveed check this answer: https://stackoverflow.com/a/53360802/2469308 You will get the idea on how to do it. – Madhur Bhaiya Nov 20 '18 at 20:35
Thank you very much got it :) – Musayyab Naveed Nov 20 '18 at 20:41
@MusayyabNaveed do consider upvoting the answer as well. Thanks :) – Madhur Bhaiya Nov 21 '18 at 03:53

score 1 · Answer 2 · answered Nov 20 '18 at 20:10

The IN clause will be easier to use than ORs. If you are using PDO you can take advantage of its execute binding and build the placeholders dynamically then just pass your array to it.

$courses = array('Eng', 'Deu', 'Bio', 'Chemi');
$placeholders = rtrim(str_repeat('?, ', count($courses)), ', ');
$query = "select * from table WHERE class = 'EFG' AND course in ({$placeholders})";
$stmt = $pdo->prepare($query);
$stmt->execute($courses);

Demo: https://3v4l.org/jcFSv (PDO bit non functional)

If this is user data you *must* use prepared statements with placeholder values. — tadman, Nov 20 '18 at 20:42

Dynamically creating OR conditions by passing an array to a query in MySQL PHP

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