将表Teacher中职称字段为"助教"人员改为"讲师"，应为（）

• A、UPDATE Teacher SET职称="助教"WHERE职称="讲师"
• B、UPDATE Teacher SET职称="讲师"WHERE职称="助教"
• C、UPDATE SET职称="助教"WHERE职称="讲师"FROMTeacher
• D、UPDATE SET职称="讲师"WHERE职称="助教"FROMTeacher