Question

I’m creating a web-based reading test. The student’s receive a random reading passage, and once they answer the questions, the passage id and their student id is placed in a table that tracks which passages they have used.

I need to return the id’s of the passages that have not already been used. I have been trying to use the NOT IN feature of MySQL.

$newpassage = "SELECT passName 
               FROM passages 
               WHERE passid NOT IN ('$passidarray');";

$passidarray is the array that contains the ids of the passages that have already been used. But every time, it still returns the passage id that has already been used. I hard coded the numbers to see if it would work and it does. But the passages they used grows the more they use the test.

For example, if there are three passages and they’ve only used 1, the result should return 2 and 3, but it is returning 1, 2, and 3. Then once they’ve used 2, it should only return 3. But it’s returning all of them. Is there something that I am doing wrong. Any help would be greatly appreciated or even a better way of doing it.

Answer 1

SQL doesn’t use php’s array object format. Try:

$newpassage = "SELECT passName FROM passages WHERE passid NOT IN (" . implode(',', $passidarray) . ");";