如何从同一表中的另一列向后更新表中的列

Question

Hi I have a table that has a structure like below

Id	oldid	newid	dateon	currentdate	code
1	NULL	636	2022-03-07 16:02:48.960	2022-03-25 10:27:56.393	777
2	636	202	2022-03-25 10:27:56.393	2022-05-11 14:34:48.153	777
3	202	203	2022-05-11 14:34:48.153	2022-05-12 14:35:42.957	777
4	203	273	2022-05-12 14:35:42.957	2022-05-14 14:35:42.957	777
5	273	189	2022-05-14 14:35:42.957	NULL	777

Currently the column in currentdate is empty. I want to update the column of current date like mentioned above ie update column currentdate one step back from dateon column.

I tried this query, But it is updating random data

UPDATE a 
SET a.currentdate = b.dateon
FROM Table a
LEFT JOIN Table b ON b.code = a.c aodend b.oldid = a.newid

Answer 1

You could use the lead function within CTE as the following:

with cte as
(
  select *,
    lead(dateon) over (partition by code order by dateon) ld
  from table_name
)
update cte set currentdate = ld;

See demo