SQL选择组中的最大值

Question

I'm stuck on this for days now. I have 3 fields, tot_order, slsnum and ordernum. I need to get the max value in ordernum, which is a unique field and its total order number in the ordernum field. The slsnum field is based on a date, so I could have a slsnum# 18443450 repeatedly per row.

tot_order: 240, 100, 50

ordernum: 23006343, 220110021, 180872124

I need the end result like this: tot_order: 240 slsnum: 18443450 ordernum: 23006343

Answer 1

You can use a correlated subquery for this:

SELECT tot_order, slsnum, ordernum
FROM table as t1
WHERE ordernum = (SELECT max(ordernum) FROM table as t2 WHERE t2.slsnum = t1.slsnum)

That subquery in the WHERE clause references the slsnum field in the main query to grab the max(ordernum) .

Answer 2

You can do this with the following query:

Select tot_order, slsnum, ordernum
from table as t
where ordernum>=ALL(
     Select ordernum from t
 )

Answer 3

Give this a whirl..

SELECT tot_order, slsnum, ordernum
FROM YourTable
WHERE OrderNum = (SELECT Max(OrderNum) FROM YourTable) 

Answer 4

SELECT *
from table_name
where ordernum = (
  select max(ordernum) from table 
)