Question

I have 3 employers IDs: 1, 2 and 3. I am generating tasks for each one by adding a line in database and in column “for_emp” I insert IDs I want to assign this task for and could be all 3 of them separated by comma. So let’s say I got a task and “for_emp” is “1,2,3”, the employers IDs. If I would like to select all tasks for the ID 2, will I be able to select from the row that has “1,2,3” as IDs and just match “2” there ? If not, how do you suggest I insert my emp IDs into one row in database ? The db is MySQL.

Any ideas ? Thanks.

Answer 1

Don’t do it like that, you should normalize your database.

What you want to do is have a table such as task, and then task_assignee. task_assignee would have fields task_id and user_id. If a task has eg. three assignees (IDs 1, 2 and 3), then you’ll create three rows in the task_assignee table for that one task, like this:

+--------+---------+
|task_id | user_id |
+--------+---------+
|   1    |    1    [
|   1    |    2    [
|   1    |    3    [
+--------+---------+

Then it’s just a simple matter of querying the task_assignee table to find all tasks that are assigned to a given user.

Here’s an example of how to get all the tasks for user_id 2:

SELECT t.* FROM task AS t INNER JOIN task_assignee AS ta WHERE ta.user_id = 2

EDIT.

Just as a related note, even if you didn’t do it the right way (which I described in my answer previously), doing it with hacks such as LIKE would still be far from the optimal solution. If you did store a list of comma-separated values, and needed to check if eg. the value 2 is in the list, you could use the MySQL’s FIND_IN_SET function:

SELECT * FROM task WHERE FIND_IN_SET(2, for_emp)

But you shouldn’t do this unless you have no choice (eg. you’re working with someone’s shitty DB design), because it’s way more inefficient and won’t let you index the the employee ID.