根据分组更新表中的行

Question

I have a table with records of the same type with ID's and a grouping. I need to update the id's of table 1 into table 2 based on the record id from largest to smallest using the position.

Table 1

ID	Group	Name
1	A	Apple
2	A	Apple
3	B	Apple
4	B	Apple

Table 2

ID	recordid	position	group
1	1	250	A
2	2	350	A
3	null	450	A
4	null	550	A
5	3	250	B
6	4	350	B
7	null	450	B
8	null	550	B

update table2
set recordid=T1.ID
From Table1 T1
join Table2 T2 on T2.Group=T1.Group

This isn't distinct so I don't think it's right, but I can't figure it out. where?????

Answer 1

the problem is you have multiple Id per group, so you have to choose one:

update table2
set recordid= ( select top 1 T1.ID
                From Table1 T1
                join Table2 T2 on T2.Group=T1.Group
               )
where recordid is null