The UPDATE statement updates the values in EMPLOYEES. The SET clause specifies that the data in the Salary column be multiplied by 1.04 when the job code ends with a 1 and 1.025 for all other job codes. (The two underscores represent any character.) The CASE expression returns a value for each row that completes the SET clause.
update employees
      set salary=salary*
      case when jobcode like '__1' then 1.04
           else 1.025