Question

I have a table like this:

Item    Serial_No   Grade   Size    Location    Date
CQ35    A243911     4   36  A           20110127
CQ35    A243911     4   36  B           20110329
CQ35    A243911     4   36  C           20110330
CQ38    A244567     3   38  A           20110127
CQ35    A244567     3   38  B           20110128
CQ38    A244567     3   38  C           20110129
CQ35    A244567     3   38  D           20110130
CQ40    A244568     3   41  A           20110127
CQ40    A244568     3   41  B           20110129
CQ36    A244570         2   37  A           20110125

The expected results shd look like this using SQL:

Item    Serial_No   Grade   Size    Location    Date
CQ35    A243911     4   36  C           20110330
CQ35    A244567     3   38  D           20110130
CQ40    A244568     3   41  B           20110129
CQ36    A244570         2   37  A           20110125

I’m trying to extract the latest row of each Serial No.

Thanks

Answer 1

UPDATE : with date

select * 
from table as outertable
where date = (select max(date) from table where Serial_No = outertable.Serial_No)

The trick here is to do comparison in the range of Serial_No only, and the way to achieve this is with a Correlated Subquery as shown here.