mysql - 数据库：获取两个字段与获取*，传输的数据量差距大吗？

Answer 1

There is no doubt that the difference is very large, so the query follows what fields are required

Answer 2

There will be differences, but not huge differences...
In principle, it is an on-demand query, that is, just SELECTthe fields that need to be queried, especially in the case of joint table query The performance difference can be significant.

Answer 3

In principle, you can check whatever fields you need
But if I have N pages that need the same interface, but each interface requires different parameters
I don’t think anyone will go out of their way to do it. Let's write 3 different queries. . hehe. Different people have different opinions.