匹配SQL中相似的不同列

Question

I have two tables. Table A as under:

ID    |   Val1   |   Val2   | Val 3
1       55.198        200     67.501
1        68.647       205      149.011
1         150.545     210       250.124

and Table B as under:

ID_From_TableA    |   Val1   |   Val2
  1                    55.199    200   
  1                    56.156    200
  1                    68.647    205

Table A has unique value if we combine

ID and Val2

and

I want to update column Val2 of tableB with Val2 of TableA when, TableA.ID = Table2.ID_From_TableA and TableA.Val1 is approximately equal to TableB.Val1

I tried below given code but it didn't work

select B.ID, B.Val1 
B.Val2 = A.VAL1
from TableA A
left join TableB B
on A.ID_From_TableA = B.ID
where (B.VAL1-A.Val1)>1

also I tried, but didnt work

 select B.ID, B.Val1 
    B.Val2 = A.VAL1
    from TableA A
    left join TableB B
    on A.ID_From_TableA = B.ID
    where B.VAL1 like A.Val1

Can someone please help?

PS - I am using MSSQL

Answer 1

Use an update join, and make sure that TableB appears on the left side of that join:

UPDATE b
SET b.Val2 = a.Val2
FROM tableB b
INNER JOIN tableA a
    ON b.ID = a.ID AND ABS(b.Val1 - a.Val1) < 0.01;

This assumes a tolerance of less than 0.01 difference between Val1 values as implying equality. You may tune this tolerance to your needs.

Answer 2

Thanks Tim,

I tried below code and it worked like a charm..

update 
    TableB
set
    Val2 = a.Val2
from TableB b
inner join TableA a
on a.ID = bookmarking.ID and ABS(bookmarking.Val1) between a.Val2 and a.Val2