need help 'before insert'

[raoul benneth]

Hi all :)

Im newbie in mysql and a lot more newbie on triggers :( so.. i need some help to create a trigger before an insert:

In a table, i have 4 columns where i need to control the value before insert new value:

firstIn firstOut secondIn secondOut

in 'human' terms, i've to do the follow:

if new_firstIn == old_firstIn dont insert and show me some message.

I need this before insert and not before update, because for the different "jobs", the firstIn can be different, for ex.:

job = 1; firstIn = 10.00
job = 2; firstIn = 11.00

"job" is in relation with an ID so:

ID = 1; job = 1; firstIn = 10.00;
ID = 1; job = 2; firstIn = 11.00;
ID = 1; job = 3; firstIn = 10.00; <-- i need to prevent this!

Any suggest?

Thx a lot.

Raoul.