Ive got the following problem. I want to change some values of INSERT statement, e.g. there's a query:

```
INSERT INTO table(a,b) values(x,y);

```

But table has also another column **c**. I want to check (before INSERT) value of **b** from the query above and depending on one's value then set **c=z** but only for this specific row I've just inserted.

I think that some trigger can help in my problem but I've no idea how to do that. Any pseudocode would be appreciated.