You inherit a customer table and need to report the average age to marketing. Spot-checking five customers, their ages are 25, null, 0, 150, and 35. If you just run AVG in SQL, what number do you get? Do you trust it, and how would you handle it?

你接手一张客户表，要给市场部算平均年龄。抽查发现5个客户的年龄分别是25、空值、0、150和35。直接用SQL的平均函数会得到多少？这个数靠谱吗，你会怎么处理？