Where Clause Not Working While Updating Database Record in ABAP

I think there is a syntax problem in your code. The colon in the first statement adds multiple following statements and hence updating all records in the first statement.

Remove the colon in the first line and comma between SET specifiers.

Example

Try using the following statement after update:

UPDATE zemployee_jat
   SET prijs = zemployee_jat-prijs
      naam = zemployee_jat-naam
WHERE employeeid = zemployee_jat-motorid.