Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
197 views
in Technique[技术] by (71.8m points)

sql - Get the latest date from grouped MySQL data

I have the following data in my database:

|NO | model | date     | 
+---+-------+----------+
|1  | bee   |2011-12-01|
|2  | bee   |2011-12-05|
|3  | bee   |2011-12-12|
|4  | tar   |2011-12-13|

I want to get the latest date of each model group:

| model | date     | 
+-------+----------+
| bee   |2011-12-12|
| tar   |2011-12-13|

I tried:

SELECT model, date 
FROM doc
WHERE date ........????? //what is the next?
GROUP BY model
Question&Answers:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Are you looking for the max date for each model?

SELECT model, max(date) FROM doc
GROUP BY model

If you're looking for all models matching the max date of the entire table...

SELECT model, date FROM doc
WHERE date IN (SELECT max(date) FROM doc)

[--- Added ---]

For those who want to display details from every record matching the latest date within each model group (not summary data, as asked for in the OP):

SELECT d.model, d.date, d.color, d.etc FROM doc d
WHERE d.date IN (SELECT max(d2.date) FROM doc d2 WHERE d2.model=d.model)

MySQL 8.0 and newer supports the OVER clause, producing the same results a bit faster for larger data sets.

SELECT model, date, color, etc FROM (SELECT model, date, color, etc, 
  max(date) OVER (PARTITION BY model) max_date FROM doc) predoc 
WHERE date=max_date;

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...