SQL aggregate query help needed

[davidib]

I have a database table that contains three columns: var_name, var_value and timestamp. var_name and var_value are both integers and timestamp is a date/time field. There are many rows for each value of var_name containing a different var_value and the timestamp is when the row was written.

I need a single SQL query that will return me the latest var_value for each var_ref in the table but my SQL skills aren't good enough for the task! Can someone help?

Thanks

 

[PDreyer]

...table contains three columns: var_name, var_value and timestamp...
need latest var_value for each var_ref...

Where does var_ref come from?

select var_ref,var_value 
from yourtable a join 
(select var_name as var_ref,max(timestamp) timestamp 
 from yourtable group by var_name
) b
on a.var_name=b.var_ref
 and a.timestamp=b.timestamp