My original data is as follows:
sid id amount 1 12 30 2 45 30 3 45 50 4 78 80 5 78 70
The desired output is as follows:
sid id amount 1 12 30 2 45 30 3 45 30 4 78 80 5 78 80
The purpose is to get the amount of the first occurrence of id and update the amount when it appears the second time I'm trying the following code:
UPDATE foo AS f1 JOIN ( SELECT cur.sl, cur.id, cur.amount AS balance FROM foo AS cur JOIN foo AS prev ON prev.id = cur.id GROUP BY cur.tstamp ) AS p ON p.id = a.id SET a.amount = p.amount ;
P粉9044509592024-01-29 20:23:49
Join the table to a query that returns the minimum value sid
for each id
and returns itself again to get the value with that minimum sid## Rows of #:
UPDATE tablename t1 INNER JOIN ( SELECT MIN(sid) sid, id FROM tablename GROUP BY id ) t2 ON t2.id = t1.id AND t2.sid < t1.sid INNER JOIN tablename t3 ON t3.sid = t2.sid SET t1.amount = t3.amount;View
Demo.
ROW_NUMBER() window function, you only need 1 connection to complete:
UPDATE tablename t1 INNER JOIN ( SELECT *, ROW_NUMBER() OVER (PARTITION BY id ORDER BY sid) rn FROM tablename ) t2 ON t2.id = t1.id SET t1.amount = t2.amount WHERE t2.rn = 1;View
Demo.