MySQL - Selecting a weeks worth of data from week beginning date - mysql

Question

Trying to do a select but can't seem to master the art of this particular one.
This is what I have tried:
select user_id,date,monday_am_task from users,week,timesheet_submission where user_id='1' and date='2015-04-06';
However it says it is too ambiguous. This is basically what I want to do. If the user_id=1 and the date is in between 2015-04-06 then show the data. By between and the date I mean this, I have setup a week table, this includes the week_number, week_id and date. Date is referred to as the week commencing date. So with my select statement I am trying to select the date that will pull all the data for that week, if that makes sense?
Week Table:
mysql> select * from week;
+---------+------+------------+
| week_id | week | date |
+---------+------+------------+
| 1 | 1 | 2014-12-29 |
| 2 | 2 | 2015-01-05 |
| 3 | 3 | 2015-01-12 |
| 4 | 4 | 2015-01-19 |
| 5 | 5 | 2015-01-26 |
| 6 | 6 | 2015-02-02 |
| 7 | 7 | 2015-02-09 | etc...
Users:
mysql> select user_id, username, level from users;
+---------+----------+-------+
| user_id | username | level |
+---------+----------+-------+
| 1 | tom | 1 |
| 2 | owain | 2 |
+---------+----------+-------+
2 rows in set (0.00 sec)
mysql> select user_id, date, timesheet_id, monday_am_task from timesheet_submission;
+---------+---------------------+--------------+----------------+
| user_id | date | timesheet_id | monday_am_task |
+---------+---------------------+--------------+----------------+
| 1 | 2015-04-10 12:44:54 | 34 | 5 |
+---------+---------------------+--------------+----------------+
1 row in set (0.00 sec)

Answer 1

This error happens when a column name exists in one or more of the selected tables. In this case, it appears to be user_id because it is in both users and timesheet_submission.
In addition, while it is all personal preference, many people prefer to use the JOIN syntax instead of listing multiple tables in the FROM clause. The second option creates a Cartesian product, which is what you are experiencing, and unless you set the proper conditions to relate a table, you can get very odd results like the ones you have now.
In short, the join syntax may look like this:
SELECT [columns]
FROM table1 t1
JOIN table2 t2 ON t2.relatedColumn = t1.relatedColumn;
For your tables, you can join users to timesheet_submission, and timesheet_submission to week, although that one is tricky because there is no direct link. To break my answer down a bit, I would start by getting all timesheet submissions for user_id 1 with a join like this:
SELECT u.user_id, ts.date, ts.monday_am_task
FROM users u
JOIN timesheet_submission ts ON ts.user_id = u.user_id AND u.user_id = 1;
Don't forget to use the table alias in select, or you'll get the ambiguity error again. As far as the date, if I were writing this query I would just include the condition that the timesheet date is between your given date, and six days later [since between is inclusive, if you go seven days later you will get the next date as well]. Try this:
SELECT u.user_id, ts.date, ts.monday_am_task
FROM users u
JOIN timesheet_submission ts ON ts.user_id = u.user_id AND u.user_id = 1
WHERE ts.date BETWEEN '2015-04-06' AND DATE_ADD('2015-04-06', INTERVAL 6 DAY);
Here is more on JOINS and on the DATE_ADD function.