mysql - mysql选择最大值

Question

一张桌子

MODEL(IDMODEL inc., NAME text)

一张桌子

DOC(IDDOC inc., NAME text, RELEASE numeric, IDMODEL numeric)

DOC 中的记录证实DOC.IDMODEL == MODEL.IDMODEL.

我想从中选择DOC具有最大值的所有记录RELEASE。

模型数据：

"1" "specification"
"2" "cahier de test"

来自 DOC 的数据：

iddoc   name        release idmodel
"1" "doc 1.1"   "1" "1"
"2" "doc 1.2"   "2" "1"
"3" "doc 2.1"   "1" "2"
"4" "doc 2.2"   "2" "2"
"5" "doc 2.3"   "3" "2"  > required
"6" "doc 1.3"   "3" "1"
"7" "doc 1.4"   "4" "1"  > required
"8" "doc 2 bis.1"   "1" "2"
"9" "doc 2 bis.2"   "2" "2"
"10" "doc 2 bis.3"  "3" "2"  > required

你能帮我做 SELECT 命令吗？

此致。

Answer 1

通过使用子选择尝试这种方式：

SELECT * 
FROM DOC 
WHERE release=(
    SELECT max(release) FROM DOC
    )

或者

 SELECT * from DOC ORDER BY release DESC LIMIT 1;

Answer 2

如果我正确理解您的问题，这应该返回您需要的行：

SELECT doc.*
FROM
  doc INNER JOIN (SELECT idmodel, MAX(release) As max_release
                  FROM doc
                  GROUP BY idmodel) mx
  ON doc.idmodel = mx.idmodel AND doc.release=max_release

请在此处查看小提琴。