Question

I have table structure like this:

Id    Name      Rank      Date
-----------------------------------
1     test      1000      2012-1-11

2     test      7000      2012-1-10

3     test2     2000      2012-1-11

4     test2     200       2012-1-10

5     test3     4000      2012-1-10

6     test4     6500      2012-1-11

Consider today date is 2012-1-11
Yesterday date is 2012-1-10

In single query i get the difference between the each user name for today and yesterday’s date.
i.e test has 7000 rank on yesterday and 1000 on today. So the result is 6000
Similarly test2 has -1800.

I need the output as:

Name     Difference (Orderby the difference Desc)
--------------------
test      6000
test2     -1800

If the today date or yesterday date’s record is not available then we will not take this record to calculation.

Is this possible in PHP MySQL?

Answer 1

How about this? (not very clear what you are trying to achieve though..) Pleaes comment.

• SQLFIDDLE DEMO

Code:

select b.id, b.name, (b.rank-a.rank) diff
from t1 a
left join t1 b
on b.date < a.date
and b.name = a.name
having not diff is null
;

Results:

ID  NAME    DIFF
2   test    6000
4   test2   -1800

Edit as per OP’s comment:

Notice that I have added extra few records to your sample table for triggering out conditions.

• SQLFIDDLE DEMO2

Code2:

select b.id, b.name,b.rank AS New,
b.Date new_date,
a.Rank as Old, a.date as old_date, 
(b.rank-a.rank) diff
from t1 a
left join t1 b
on b.name = a.name
where b.date > a.date and b.date <= Now()
and datediff(b.date, a.date) = 1
having not diff is null and diff <> 0
order by diff desc
;

Results:

ID  NAME    NEW     NEW_DATE            OLD     OLD_DATE            DIFF
3   test    8000    January, 12 2012    1000    January, 11 2012    7000
4   test2   2000    January, 11 2012    200     January, 10 2012    1800
1   test    1000    January, 11 2012    7000    January, 10 2012    -6000