MySQL queries the total number of records after using GROUP by

Test table

To find out what a user is doing, combine the actions

The following SQL can be used to achieve the purpose

SELECT  as Operation  from Test GROUP  by NAME

Then to find out how many such users, directly after the Select plus the count () function has no effect.

One solution is to use the query result as a table, with select COUNT (*) in the outer layer

SELECT COUNT (*from(SELECT as operation from test GROUP  by   as T

Another easier way is to use the DISTINCT keyword

SELECT COUNT (DISTINCT from test

MySQL queries the total number of records after using GROUP by