Question

i have a List and want to select rows by their ID. are this affect the queries performance and better alternate to do that.

Answer 1

If you have a list and do the following kind of query :

select * from your_table where id = 123
select * from your_table where id = 345
select * from your_table where id = 679

for each one of the items of your list, you’ll end up doing a lot of queries — which, as you can guess, is not that good for performances.

An idea might be to group those queries, like this :

select * from your_table where id in (123, 345, 679)

To do less queries : only one here, instead of three.

This means a bit more logic in your code, to get the results from the database, of course ; but it will generally help, when it comes to performances.

Note though : you should not use too much ids in a single in() clause — which means you might end up doing several queries — each one working on several ids.