MySQL：如何仅使用一个查询获取表中不存在的ID的百分比

Question

Actually I am using two queries to get

1. the sum of existing IDs in a table
2. the missing IDs in the same table

then I use PHP to calculate the percentage of the missing IDs in this table.

I am sure there are better ways and I am searching the best one, in example using only one query to directly receive the percentage value from the mysql query and with the fastest performance .

Let's say my table name is my_table and the column with the values is named id . There are only unique ids in the column from 1 to *, and some ids are missing between. Example rows (values): 1 , 2 , 3 , 4 , 7 , 8 , 9 , 22, ....

Which mysql query do you think would be the best way to directly receive the percentage of missing ids in this table?

Answer 1

   SELECT (MAX(id)-count(id)) / MAX(id) * 100 as MissingRate
    FROM my_table

Answer 2

This will give you the correct percentage. It will calculate it, based that you look every missing number like a missing number.

SELECT Count(id)/MAX(id) as percent
    FROM my_table