Database(SYSNAME)    DataFileSize(INT)    Batch(INT PK)
DatabaseA                  30              1
DatabaseB                  15              2
DatabaseC                  40              3
...
DatabaseA                  31              7
DatabaseB                  15              8
DatabaseC                  41              9

SELECT DatabaseName, MAX(Batch) AS LastBatch INTO #temp
FROM tblDatabaseSizes
GROUP BY DatabaseName

SELECT * FROM tblDatabaseSizes
WHERE Batch IN (SELECT LastBatch FROM #temp)
ORDER BY DatabaseName

DROP TABLE #temp

DatabaseA          31             7
DatabaseB          15             8
DatabaseC          41             9

SELECT DatabaseName,Datafilesize,batch
FROM
(
SELECT DatabaseName,Datafilesize,batch,ROW_NUMBER() OVER (PARTITION BY databasename ORDER BY batch DESC) AS Seq
FROM Table
)t
WHERE Seq=1

SELECT t.DatabaseName,t.Datafilesize,t.batch
FROM table t
INNER JOIN (SELECT DatabaseName,MAX(batch) AS Latest
            FROM table
            GROUP BY DatabaseName
            )t1
On t1.DatabaseName = t.DatabaseName
AND t1.Latest = t.batch