从查询返回最大值

Question

I'm trying to create a query to return the file with the max version, independent of the value of the server. How could I do that?

actual table data:

server    filename    v4    date
local     code1.zip   41    0000-00-00
remote    code1.zip   39    0000-00-00
local     code1.zip   28    0000-00-00
remote    code1.zip   21    0000-00-00
local     code1.zip   32    0000-00-00
remote    code1.zip   27    0000-00-00

the query:

SELECT
    server,
    filename,
    max(v4) as v4,
    date
FROM
    table
WHERE
    date ='0000-00-00'

GROUP BY
    filename,
    server,
    date

Actual result:

server    filename    v4    date
local     code1.zip   41    0000-00-00
remote    code1.zip   39    0000-00-00

Expected result:

server    filename    v4    date
local     code1.zip   41    0000-00-00

EDIT: It's for MySQL

Thanks in advance.

Answer 1

If you just want the row with largest v4 you can use this

SELECT
    server,
    filename,
    v4,
    date
FROM
    `table`
WHERE
    date ='0000-00-00'
ORDER BY v4 DESC
LIMIT 1

to get max V4 for each filename, first you get max(v4) group by filename then INNER JOIN back with table like below

SELECT T1.server,T1.filename,T1.v4,T1.date
FROM
`table` T1 INNER JOIN
    (SELECT filename,max(v4) as maxv4
     FROM `table`
     WHERE date = '0000-00-00'
     GROUP BY filename)T2
ON T1.filename = T2.filename AND T1.v4 = T2.maxV4
WHERE date = '0000-00-00';

Answer 2

To get the the max version you only have to do:

SELECT MAX(version) FROM table 

If you also want the filename (if you have another column id ):

SELECT t2.filename, t2.maxver
FROM table t1 INNER JOIN
(SELECT id, MAX(version) maxver 
FROM table 
GROUP BY id) t2 ON t1.id=t2.id
ORDER BY t2.maxver DESC
LIMIT 1

If you also want the filename (if you haven't another column id , use filename ):

SELECT t2.filename, t2.maxver 
FROM table t1 INNER JOIN
     (SELECT filename, MAX(version) maxver 
      FROM table 
      GROUP BY filename) t2 ON t1.filename=t2.filename
      WHERE t2.maxver = (SELECT MAX(version) FROM table)

There are many ways to do it.

Answer 3

You could use this query:

Select Top 1 *
From table
Where v4 = (
SELECT
    max(v4) as v4,
FROM
    table
WHERE
    date ='0000-00-00'

GROUP BY
    v4
)