如果更改了值，则更新mysql db并更改其他值

Question

in my database i have a updateinfo with timestamp etc. wich should updated everytime the values has changes/update.

actually i check at first if there has changed value (old) and value (new) only if its, i add the update value with new updateinfos.

Now i ask myself how i can do it easier and faster. Normaly mysql dont update somethink if the value has not changes. But whats about my updateinfos. If i add them mysql will update them everytime. How can i do it that mysql only set the new updateinfos if there is really a changed value?

For Example

mysql SET a=1, b=2, Updateinfo='TIMESTAMP+IP'

What i looking for is a kind like this

mysql SET a=1, b=2, (Updateinfo='Timestamp+IP' ONLY IF a or b has updated)

So is there a way to add the field Updateinfo='Timestamp...' to the query if there is a change by one of the SET a=1, b=2?

Hope i could explain what i'm looking for.

Answer 1

Something like this? It's only a pseudo-code, but you get the idea

run_query("UPDATE table SET a=1, b=2");
if(success == run_query){
    run_query("UPDATE table SET Updateinfo='Timestamp+IP' WHERE a=1 AND b=2");
} else {
    //some other things...
}

Revise #1

$a = 'somevalue';
$b = 'somevalue2';

$result = fetch -> run_query('SELECT a, b FROM table');
$existingA = $result["a"];
$existingB = $result["b"];

if(($existingA != $a) || ($existingB != $b)){
    run_query("UPDATE table SET a=$a, b=$b, Updateinfo='Timestamp+IP'");
}