SQL - 查询某一字段值相同而另一字段值最大的记录

1.

SELECT a.* FROM app a
WHERE a.app_version = (SELECT MAX(b.app_version) FROM app b WHERE b.app_name = a.app_name)
ORDER BY a.app_name;

2.

SELECT a.* FROM app a
WHERE NOT EXISTS(SELECT 1 FROM app b WHERE b.app_name = a.app_name AND b.app_version > a.app_version)
ORDER BY a.app_name;

3.

SELECT a.*
FROM app a, (SELECT app_name, MAX(app_version) AS app_version FROM app GROUP BY app_name) b
WHERE a.app_name = b.app_name
AND a.app_version = b.app_version
ORDER BY a.app_name;

4.

SELECT a.*
FROM app a INNER JOIN (SELECT app_name, MAX(app_version) AS app_version FROM app GROUP BY app_name) b
ON a.app_name = b.app_name
AND a.app_version = b.app_version
ORDER BY a.app_name;