getting wrong values after joining tables - MySQL - PHP - php

Question

I have to generate a report using 4 tables, I tried a lot of joins, but I get wrong values :(
Hope someone will help me.
StaffAssign Table:
----------------------------
| Tid | StaffId | Planned |
----------------------------
| 123 | 2 | 10:00:00 |
| 123 | 4 | 05:00:00 |
| 124 | 2 | 09:00:00 |
----------------------------
ActualEffort Table:
--------------------------------------------
| Tid | StaffId | ActualEffort | logdate |
--------------------------------------------
| 123 | 2 | 05:00:00 |2012-09-01|
| 123 | 4 | 05:00:00 |2012-09-01|
| 123 | 2 | 06:00:00 |2012-09-03|
| 124 | 2 | 09:00:00 |2012-09-04|
--------------------------------------------
ProjectList Table:
-------------------
| ProjectId | Tid |
-------------------
| 1 | 123 |
| 2 | 124 |
-------------------
ProjectName Table:
-------------------
| Id | name |
-------------------
| 1 | project1 |
| 2 | project2 |
-------------------
Below is the Query I'm using:
SELECT P.id AS projectid,P.name,
SEC_TO_TIME(SUM(TIME_TO_SEC(A.planned)))planned,SEC_TO_TIME(SUM(TIME_TO_SEC(E.actualeffort)))actual FROM actualeffort E
INNER JOIN staffassign A ON A.tid = E.tid
INNER JOIN projectlist L ON L.tid = A.tid
INNER JOIN projectname P ON P.id = L.projectid
WHERE E.logdate BETWEEN FROM_UNIXTIME('1346475600') AND FROM_UNIXTIME('1348290000')
GROUP BY P.id
I'm getting this:
---------------------------------------------
| projectid | name | planned | actual |
---------------------------------------------
| 1 | project1 | 15:00:00| 12:00:00 |
| 2 | project2 | 09:00:00| 09:00:00 |
---------------------------------------------
But it should be like:
---------------------------------------------
| projectid | name | planned | actual |
---------------------------------------------
| 1 | project1 | 15:00:00| 16:00:00 |
| 2 | project2 | 09:00:00| 09:00:00 |
---------------------------------------------
I'm very confused that, I don't know where I'm going wrong with the joins.
Someone please help me, I'm struck with this.

Answer 1

The WHERE filter may be wrong. Note that first datetime in the condition starts at '08:00:00' -
SELECT FROM_UNIXTIME('1346475600') dt1, FROM_UNIXTIME('1348290000') dt2;
+---------------------+---------------------+
| dt1 | dt2 |
+---------------------+---------------------+
| 2012-09-01 08:00:00 | 2012-09-22 08:00:00 |
+---------------------+---------------------+
The type of ActualEffort.logdate field is DATE; the value '2012-09-01' is less then '2012-09-01 08:00:00'. So change this condition or use DATE function -
WHERE
E.logdate BETWEEN
DATE(FROM_UNIXTIME('1346475600')) AND DATE(FROM_UNIXTIME('1348290000'))
(edited)
For one thing, when you join StaffAssign and ActualEffort on the Tid column only, you get a mini-Cartesian product for Tid=123 in particular, because both tables contain more than one row with that Tid and there's no other specific condition to establish a 1:1 or, at most, 1:N relationship between the rows.
But in fact, 1:N wouldn't do either: although it wouldn't give you the Cartesian product effect, it would result in duplicated values on one side and, as a consequence, in a distorted SUM.
Therefore, data in StaffAssign and those in ActualEffort must be aggregated separately, then joined, something like this:
SELECT
pl.ProjectId,
pn.name,
sa.Planned,
ae.ActualEffort
FROM ProjectList pl
JOIN ProjectName pn
ON pn.Id = pl.ProjectId
LEFT JOIN (SELECT Tid, SEC_TO_TIME(SUM(TIME_TO_SEC(Planned))) Planned FROM StaffAssign GROUP BY Tid) sa
ON sa.Tid = pl.Tid
LEFT JOIN (SELECT Tid, SEC_TO_TIME(SUM(TIME_TO_SEC(ActualEffort))) ActualEffort FROM ActualEffort GROUP BY Tid) ae
ON ae.Tid = pl.Tid
GROUP BY ProjectId;

Answer 2

There is an error in your SQL:
You wan't to join p.ProjectID not p.id

Answer 3

Try this query
SELECT P.id AS projectid,P.name,
SEC_TO_TIME(SUM(TIME_TO_SEC(A.planned)))planned,SEC_TO_TIME(SUM(TIME_TO_SEC(E.actualeffort)))actual FROM actualeffort E
INNER JOIN staffassign A ON A.tid = E.tid
INNER JOIN projectlist L ON L.tid = A.tid
INNER JOIN projectlist L ON L.tid = E.tid // you have not added this line
INNER JOIN projectname P ON P.id = L.projectid
WHERE E.logdate BETWEEN FROM_UNIXTIME('1346475600') AND FROM_UNIXTIME('1348290000')
GROUP BY P.id
a join between L and E should be present.