Question

I have a relationships table, the table looks something like this

 ------------------------
| client_id | service_id |
 ------------------------
| 1         | 1          |
| 1         | 2          |
| 1         | 4          |
| 1         | 7          |
| 2         | 1          |
| 2         | 5          |
 ------------------------

I have a list of new permissions I need to add, what I’m doing right now is, for example, if I have to add new permissions for the client with id 1, i do

DELETE FROM myTable WHERE client_id = 1
INSERT INTO ....

Is there a more efficient way I can remove only the ones I won’t insert later, and add only the new ones?

Answer 1

yes, you can do this but in my humble opinion, it’s not really sql dependent subject. actually it depends on your language/platform choice. if you use a powerful platform like .NET or Java, there are many database classes like adapters, datasets etc. which are able to take care of things for you like finding the changed parts, updating/inserting/deleting only necessery parts etc.

i prefer using hibernate/nhibernate like libraries. in this case, you don’t even need to write sql queries most of the time. just do the things at oop level and synchronize with the database.