Mysql 根据日期将多行数据放到一行

Question

I have the following data in a MYSQL table.

ID	NAME	PHONENO	EMAIL	TMDate
1234	Sarah	0884100300		1-Jan-21
1234	Sarah	0881500900		5-Mar-21
1234	Sarah		Sarah@gmail.com	10-Mar-21
0001	James	09991234567		31-Dec-20
0001	James		james@yahoo.com	31-Dec-20

The table contain email and phone numbers for customers. If the phonenumber or email is updated, the data is recorded on a new row. The TMDate column shows when the record was collected.

I want the final output to be as follows:

ID	NAME	PHONENO	EMAIL
1234	Sarah	0881500900	example@gmail.com
0001	James	09991234567	james@yahoo.com

My approach was to first pull the phone numbers based on max data using script below and then pull the emails using a script with similar logic and then do inner join of the two

 SELECT t1.id,
   t1.name
   t2.PHONENO,
   t2.max_date
 FROM phoneemail t1
  INNER JOIN
   (SELECT id,PHONENO, MAX(TMDATE) as max_date FROM phoneemail group by id,phoneno where t1.phoneno 
 is not null) t2
   ON t1.id = t2.id

My approach is not working as I am still getting duplicate records

Answer 1

MySQL does not have a "first" or "last" aggregation function. So, one method is to use window functions:

select distinct id, name,
       first_value(phone ignore nulls) over (partition by id order by tmdate desc) as phone,
       first_value(email ignore nulls) over (partition by id order by tmdate desc) as email
from (select distinct id, name from t) t;

Happily, first_value() has the ignore nulls option.

Answer 2

The columns PHONENO and EMAIL my have been updated in different dates, so getting the latest date for each ID will not help.

If your version of MySql is 8.0+ you can do it with FIRST_VALUE() window function, which does not support IGNORE NULLS , so conditional sorting is also needed:

SELECT DISTINCT ID, NAME,
       FIRST_VALUE(PHONENO) OVER (PARTITION BY ID, NAME ORDER BY PHONENO IS NULL, TMDate DESC) PHONENO,
       FIRST_VALUE(EMAIL) OVER (PARTITION BY ID, NAME ORDER BY EMAIL IS NULL, TMDate DESC) EMAIL
FROM phoneemail 

For prior versions you need 2 correlated subqueries:

SELECT DISTINCT p1.ID, p1.NAME,
  (SELECT p2.PHONENO FROM phoneemail p2 
   WHERE (p2.ID, p2.NAME) = (p1.ID, p1.NAME) AND p2.PHONENO IS NOT NULL 
   ORDER BY TMDate DESC LIMIT 1) PHONENO,
  (SELECT p3.EMAIL FROM phoneemail p3 
   WHERE (p3.ID, p3.NAME) = (p1.ID, p1.NAME) AND p3.EMAIL IS NOT NULL 
   ORDER BY TMDate DESC LIMIT 1) EMAIL 
FROM phoneemail p1

See the demo .
Results:

ID	NAME	PHONENO	EMAIL
1234	Sarah	0881500900	Sarah@gmail.com
0001	James	09991234567	james@yahoo.com