Write speed instances compared to select * and select all fields

From a very early time, listening to the teacher said select * from table is much slower than select a,b,c,d from table. Never tested for 3 years. Today is nothing to test a test, contingency do not know, a test scare jump.

Of course, the following is purely test, not applied to the actual project. If you have any comments and suggestions, please advise.

Number	* Number Enquiry	Field Query
First time
Second time
Third time

The test code is as follows: