Request optimisation - sql

Question

I have two tables, on one there are all the races that the buses do
dbo.Courses_Bus
|ID|ID_Bus|ID_Line|DateHour_Start_Course|DateHour_End_Course|
On the other all payments made in these buses
dbo.Payments
|ID|ID_Bus|DateHour_Payment|
The goal is to add the notion of a Line in the payment table to get something like this
dbo.Payments
|ID|ID_Bus|DateHour_Payment|Line|
So I tried to do this :
/** I first added a Line column to the dbo.Payments table**/
UPDATE
Table_A
SET
Table_A.Line = Table_B.ID_Line
FROM
[dbo].[Payments] AS Table_A
INNER JOIN [dbo].[Courses_Bus] AS Table_B
ON Table_A.ID_Bus = Table_B.ID_Bus
AND Table_A.DateHour_Payment BETWEEN Table_B.DateHour_Start_Course AND Table_B.DateHour_End_Course
And this
UPDATE
Table_A
SET
Table_A.Line = Table_B.ID_Line
FROM
[dbo].[Payments] AS Table_A
INNER JOIN (
SELECT
P.*,
CP.ID_Line AS ID_Line
FROM
[dbo].[Payments] AS P
INNER JOIN [dbo].[Courses_Bus] CP ON CP.ID_Bus = P.ID_Bus
AND CP.DateHour_Start_Course <= P.Date
AND CP.DateHour_End_Course >= P.Date
) AS Table_B ON Table_A.ID_Bus = Table_B.ID_Bus
The main problem, apart from the fact that these requests do not seem to work properly, is that each table has several million lines that are increasing every day, and because of the datehour filter (mandatory since a single bus can be on several lines everyday) SSMS must compare each row of the second table to all rows of the other table.
So it takes an infinite amount of time, which will increase every day.
How can I make it work and optimise it ?

Answer 1

Assuming that this is the logic you want:
UPDATE p
SET p.Line = cb.ID_Line
FROM [dbo].[Payments] p JOIN
[dbo].[Courses_Bus] cb
ON p.ID_Bus = cb.ID_Bus AND
p.DateHour_Payment BETWEEN cb.DateHour_Start_Course AND cb.DateHour_End_Course;
To optimize this query, then you want an index on Courses_Bus(ID_Bus, DateHour_Start_Course, DateHour_End_Course).
There might be slightly more efficient ways to optimize the query, but your question doesn't have enough information -- is there always exactly one match, for instance?
Another big issue is that updating all the rows is quite expensive. You might find that it is better to do this in loops, one chunk at a time:
UPDATE TOP (10000) p
SET p.Line = cb.ID_Line
FROM [dbo].[Payments] p JOIN
[dbo].[Courses_Bus] cb
ON p.ID_Bus = cb.ID_Bus AND
p.DateHour_Payment BETWEEN cb.DateHour_Start_Course AND cb.DateHour_End_Course
WHERE p.Line IS NULL;
Once again, though, this structure depends on all the initial values being NULL and an exact match for all rows.

Answer 2

Thank you Gordon for your answer.
I have investigated and came with this query :
MERGE [dbo].[Payments] AS p
USING [dbo].[Courses_Bus] AS cb
ON p.ID_Bus= cb.ID_Bus AND
p.DateHour_Payment>= cb.DateHour_Start_Course AND
p.DateHour_Payment<= cb.DateHour_End_Course
WHEN MATCHED THEN
UPDATE SET p.Line = cb.ID_Ligne;
As it seems to be the most suitable in an MS-SQL environment.
It also came with the error :
The MERGE statement attempted to UPDATE or DELETE the same row more than once. This happens when a target row matches more than one source row. A MERGE statement cannot UPDATE/DELETE the same row of the target table multiple times. Refine the ON clause to ensure a target row matches at most one source row, or use the GROUP BY clause to group the source rows.
I understood this to mean that it finds several lines with identical
[p.ID_Bus= cb.ID_Bus AND
p.DateHour_Payment >= cb.DateHour_Start_Course AND
p.DateHour_Payment <= cb.DateHour_End_Course]
Yes, this is a possible case, however the ID is different each time.
For example, if two blue cards are beeped at the same time, or if there is a loss of network and the equipment has been updated, thus putting the beeps at the same time. These are different lines that must be treated separately, and you can obtain for example:
|ID|ID_Bus|DateHour_Payments|Line|
----------------------------------
|56|204|2021-01-01 10:00:00|15|
----------------------------------
|82|204|2021-01-01 10:00:00|15|
How can I improve this query so that it takes into account different payment IDs?
I can't figure out how to do this with the help I find online. Maybe this method is not the right one in this context.