MySQL Inner Join On Clause Field Not Found - mysql

Question

My current tables look like this:
Lessons:
+-----------------------------------+
| ID | Name | StartDate | Repeats |
|----|-------|------------|---------|
| 1 | Maths | 2014-05-05 | 5 |
| 2 | Lunch | 2014-05-05 | 1 |
| 3 | Comp | 2014-05-05 | 7 |
+-----------------------------------+
LessonTimes:
+-------------------------------------+
| ID | LessonID | StartTime | EndTime |
|----|----------|-----------|---------|
| 1 | 1 | 10:00:00 | 5 |
| 2 | 2 | 12:25:00 | 1 |
| 3 | 3 | 14:00:00 | 7 |
+-------------------------------------+
Tally:
+----+
| ID |
|----|
| 1 |
| 2 |
| . |
| . |
+----+
I have events that repeat on a certain number of days with a specific start date. The current query I have is:
SELECT E.ID
, E.Name
, E.StartDate
, E.Repeats
, A.ShowDate
, DATEDIFF(E.StartDate, A.ShowDate) diff
, T.StartTime
, DATE_ADD(A.ShowDate, INTERVAL T.StartTime HOUR_SECOND) ShowTime
FROM Planner_Lessons E
, ( SELECT DATE_ADD('2014-05-05 00:00:00',INTERVAL ID DAY ) ShowDate
FROM `Planner_Tally`
WHERE (DATE_ADD('2014-05-05 00:00:00',INTERVAL ID DAY )<= '2014-05-30 00:00:00')
ORDER
BY Id ASC
) A
LEFT
JOIN Planner_LessonTimes T
ON T.LessonID = E.ID
WHERE MOD(DATEDIFF(E.StartDate, A.ShowDate), E.Repeats) = 0
AND A.ShowDate >= E.StartDate
But the error I get is saying that the field E.ID cannot be found in the "ON" clause.
The original question I found the query on is here - PHP/MySQL: Model repeating events in a database but query for date ranges

Answer 1

Here is your query, formatting so one can read it:
SELECT E.ID, E.Name, E.StartDate, E.Repeats, A.ShowDate, DATEDIFF(E.StartDate, A.ShowDate) AS diff,
T.StartTime, DATE_ADD(A.ShowDate, INTERVAL T.StartTime HOUR_SECOND) AS ShowTime
FROM Planner_Lessons AS E,
(SELECT DATE_ADD('2014-05-05 00:00:00',INTERVAL ID DAY) as ShowDate
FROM `Planner_Tally`
WHERE (DATE_ADD('2014-05-05 00:00:00',INTERVAL ID DAY)<='2014-05-30 00:00:00')
ORDER BY Id ASC
) A LEFT JOIN
Planner_LessonTimes AS T
ON T.LessonID=E.ID
WHERE MOD(DATEDIFF(E.StartDate, A.ShowDate), E.Repeats)=0 AND A.ShowDate>=E.StartDate;
You are missing implicit and explicit join syntax. The columns in E are not recognized after the comma, due to MySQL scoping rules.
SELECT E.ID, E.Name, E.StartDate, E.Repeats, A.ShowDate, DATEDIFF(E.StartDate, A.ShowDate) AS diff,
T.StartTime, DATE_ADD(A.ShowDate, INTERVAL T.StartTime HOUR_SECOND) AS ShowTime
FROM Planner_Lessons E JOIN
Planner_LessonTimes T
ON T.LessonID = E.ID JOIN
(SELECT DATE_ADD('2014-05-05 00:00:00',INTERVAL ID DAY) as ShowDate
FROM `Planner_Tally`
WHERE (DATE_ADD('2014-05-05 00:00:00',INTERVAL ID DAY)<='2014-05-30 00:00:00')
ORDER BY Id ASC
) A
ON MOD(DATEDIFF(E.StartDate, A.ShowDate), E.Repeats)=0 AND A.ShowDate>=E.StartDate;
I switched the left join to inner join, because the where clause undoes the outer join.

Answer 2

You have missed JOIN condition for subquery aliased as A . Assuming Planner_Tally table contains column ID , you can add joining condition ON A.ID=E.ID as shown below
SELECT E.ID, E.Name, E.StartDate, E.Repeats, A.ShowDate,
DATEDIFF(E.StartDate, A.ShowDate) AS diff, T.StartTime,
DATE_ADD(A.ShowDate, INTERVAL T.StartTime HOUR_SECOND) AS ShowTime
FROM Planner_Lessons AS E
LEFT JOIN Planner_LessonTimes AS T ON T.LessonID=E.ID
LEFT JOIN (
SELECT DATE_ADD('2014-05-05 00:00:00',INTERVAL ID DAY) as ShowDate,ID
FROM `Planner_Tally`
WHERE (DATE_ADD('2014-05-05 00:00:00',INTERVAL ID DAY)<='2014-05-30 00:00:00')
) A ON A.ID=E.ID
WHERE MOD(DATEDIFF(E.StartDate, A.ShowDate), E.Repeats)=0
AND A.ShowDate>=E.StartDate
ORDER BY E.Id ASC

Answer 3

As an aside, consider the following... (ints is a table of integers from 0-9)
EXPLAIN
SELECT * FROM ints WHERE '2014-05-05 00:00:00' + INTERVAL i DAY < '2014-30-30 00:00:00'\G
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: ints
type: index
possible_keys: NULL
key: PRIMARY
key_len: 4
ref: NULL
rows: 10
Extra: Using where; Using index
1 row in set (0.00 sec)
EXPLAIN
SELECT * FROM ints WHERE i < DATEDIFF('2014-05-30 00:00:00','2014-05-05 00:00:00')\G
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: ints
type: index
possible_keys: PRIMARY
key: PRIMARY
key_len: 4
ref: NULL
rows: 10
Extra: Using where; Using index
1 row in set (0.00 sec)
As you can see, although both queries are logically identical, the first registers NULL for possible_keys.
We have now reached the total extent of my knowledge of indices.