Question

Need a mysql query (UNIQUE, DISTINCT etc)

Asked by: kiranvj

Hi Experts,

I need help in a mysql query to get the correct result. I am looking for a single query to do this in one step


I have these in my table

lid   did   lt     ln     stime
1      1    4      5     2009-09-20 12:45:32
2      2    4      5     2009-09-20 12:46:32
3      2    4      5     2009-09-20 12:47:52
4      3    4      5     2009-09-20 12:48:12
5      1    4      5     2009-09-20 12:49:52
6      1    4      5     2009-09-20 12:50:12
 


I want the result like this

lid   did   lt     ln     stime
2      2    4      5     2009-09-20 12:46:32
4      3    4      5     2009-09-20 12:48:12
6      1    4      5     2009-09-20 12:50:12



In simple words I want distinct 'did'  and rows which has highest 'stime'.

lid, did, lt, ln has int data type, stime is date/time

Hope its clear.

Thanks in advance.

kiranvj

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Asked On
2009-09-25 at 05:37:52ID24761447
Tags

mysql

,

distinct

,

unique query

Topics

MySQL Server

,

PHP Scripting Language

,

PHP and Databases

Participating Experts
2
Points
500
Comments
7

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Answers

 

by: tonystarkPosted on 2009-09-25 at 06:02:09ID: 25422474

Try this...

select iid,distinct(did),lt,ln,stime from tablename


u can also do this like..

select * from table where iid in(2,4,6)

 

by: tonystarkPosted on 2009-09-25 at 06:11:10ID: 25422551

OOps...

Try this..

select iid,distinct(did),lt,ln,max(stime) from tablename group by did

 

by: BrianMMPosted on 2009-09-25 at 06:45:25ID: 25422863

the distinct in tonystark's solution is redundant, distinct works on the entire row.

You will probably only need to use group by to achieve your result.

select iid,did,lt,ln,max(stime) from tablename group by did

 

by: kiranvjPosted on 2009-09-25 at 07:01:53ID: 25423025

Unfortunately the above queries is not working.


this
select iid,did,lt,ln,max(stime) from tablename group by did

gives somewhat strange results

lid, did, lt, ln is from same row, but max(stime) is displayed from another row.

This is what i need.

all fields from table where did = 1 and stime is maximum (among all row which has did = 1)
all fields from table where did = 2 and stime is maximum (among all row which has did = 2)
all fields from table where did = 3 and stime is maximum (among all row which has did = 3)

 

by: BrianMMPosted on 2009-09-25 at 07:08:36ID: 25423094

try:

select  iid,did,lt,ln,stime
  from tablename as T
 where `stime` =
       ( select max(`stime`)
           from tablename
          where did = T.did )

 

by: kiranvjPosted on 2009-09-25 at 07:14:29ID: 25423152

Worked like a charm :)

Thank you all for your time and efforts.

kiranvj

 

by: kiranvjPosted on 2009-09-25 at 07:15:29ID: 31633495

Excellent, working fine

20120131-EE-VQP-002

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