Get à value display on the screen

Hello, I use HeidiSQL as a front end user (only 3 personns, i know it's REALLY BAD) and i would like to be able to get the timestamp displayed in the row/column "timestamp" (the value which is displayed on the Heidi SQLGrid) and compare it with the OLD/NEW data. I can get it by à "manual copy" but i would like to be able to get it automatically in the Trigger-before-update to compare it. I'm stuck because i can't find a way to prevent from errors when multi users update the same row (i know Heidsql is NOT made for that)

Sorry, i'm a newbie in mysql... ;-(

Any ideas ???