Question

This seems like it should be easy, but I’m banging my head against the wall. I’m creating a site in php/mysql where, when a user pulls up a day of the week, it will list assignments given to them grouped by chunks of time, e.g., 8-11, 11-14, etc.

I have a table set up like this, where the fields are intended to reference another table containing tasks. Each integer corresponds to a unique task in the tasks table.

       8-11   11-14  14-17  17-20   20-23 
Mon     1       3      4      1   2
Tues   1,3      4      5      6   7 
Wed    1,2,3    5      4      8   9 

As you can see, some days have repeating tasks at different times (e.g., on Monday, task 1 is performed during the 8-11 and 17-20 slot). And most baffling for me is how to set up the table or join multiple tables to address time slots with multiple tasks, e.g., the Wed 8-11 shift has three tasks, 1, 2, and 3.

My question: can you suggest table structure(s) that would be optimal for this, and an example query to retrieve the tasks for a given day? THANK YOU. Any help is greatly appreciated.

** EDIT ** Here’s what I’m trying to ask: looking at Wed 8-10, how can I pull the three tasks from the task table?

Answer 1

http://sqlfiddle.com/#!2/2130b/8

CREATE TABLE work_periods (work_period_id int unsigned, weekday int unsigned, description varchar(50));
CREATE TABLE tasks (task_id int unsigned, description varchar(50));
CREATE TABLE work_period_task_assignments (work_period_id int unsigned, task_id int unsigned);
INSERT INTO work_periods VALUES (1, 1, 'Mon 8-11'), (2, 1, 'Mon 11-14'), (3, 1, 'Mon 14-17');
INSERT INTO tasks VALUES (1, 'Drink Coffee'), (2, 'Make Toast'), (3, 'Do Work');
INSERT INTO work_period_task_assignments VALUES (1, 1), (1, 2), (2,3), (3,3);

SELECT p.description as period, t.description as task FROM work_periods p
INNER JOIN work_period_task_assignments wpta
ON wpta.work_period_id = p.work_period_id 
INNER JOIN tasks t
ON wpta.task_id = t.task_id 
WHERE p.weekday = 1;