MySQL语句UPDATE IF等于或大于其他什么都不做

Question

I have the following MySQL statement:

$stmt = $conn->prepare('UPDATE `equipment` SET `currentHours`= :unitHours, `lastUpdate`= :lastUpdate WHERE `equipType`= :equipType AND `unitNumber`= :unitNumber'); 

    $stmt ->execute(array(':lastUpdate'=> $dateToday, ':unitHours' => $unitHours, ':equipType'=> $equipType, ':unitNumber'=> $unitNumber));

I need to only update the currentHours if the value is equal to or greater than the value currently stored in that row. Is this possible with a MySQL statement or do I have to do it in PHP? I am new to programming so sorry in advance if this sounds like a simple question.

Answer 1

UPDATE `equipment` SET `currentHours`= :unitHours, `lastUpdate`= :lastUpdate

 WHERE `equipType`= :equipType AND `unitNumber`= :unitNumber

AND
    currentHours<:unitHours

The above updates only records with current hours lower than the input, it won't update all last update field that matches the rest of the condition.
If u want to update the field currenthours only when it is lower than the input, but update the lastupdate field regardless, then:

UPDATE `equipment` 
SET `currentHours`= IF(currentHours<:unitHours,:unitHours,currentHours), 
`lastUpdate`= :lastUpdate

WHERE `equipType`= :equipType AND `unitNumber`= :unitNumber