CODEWITHSUNDEEP
mysqlsql
hmmmm
hmmmm

Reputation: 521

How do I update MySQL column depend on last date

Lets say I have two tables

table_1

ID  Name   Status
1   John   
2   Peter  
3   Smith

table_2

ID  UID   Status  UpdateDate
1   1     B       2010-05-05
2   1     C       2011-03-02
3   3     C       2011-03-02
4   2     A       2011-03-02

What is the correct statement to update Status on table_1 according to UpdateDate on table_2.

Result should be like this

table_1

ID  Name   Status
1   John   C
2   Peter  A
3   Smith  C

Thanks.

Upvotes: 2

Views: 397

Answers (2)

Kyle Rosendo
Kyle Rosendo

Reputation: 25277

UPDATE table_1 SET Status = (
    SELECT Status FROM table_2
    WHERE UID = table_1.ID
    ORDER BY UpdateDate desc
    LIMIT 1
    );

Upvotes: 1

Jon Freedman
Jon Freedman

Reputation: 9697

To get the status for each UID:

SELECT UID, Status
FROM (
  SELECT UID, MAX(UpdateDate) LastUpdateDate
  FROM table_2
  GROUP BY UID
) l
JOIN table_2 t ON t.UID = l.UID AND t.UpdateDate = l.LastUpdateDate

To update:

UPDATE table_1 SET Status = l.Status
FROM table_1 t
JOIN (
  SELECT UID, Status
  FROM (
    SELECT UID, MAX(UpdateDate) LastUpdateDate
    FROM table_2
    GROUP BY UID
  ) l
  JOIN table_2 t ON t.UID = l.UID AND t.UpdateDate = l.LastUpdateDate
) l ON l.UID = t.ID

Upvotes: 0

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