MYSQL last login and number of logins in last 3 months

Question

I\'m trying to write a query to join a user table to an activity logging table and return the following for each user:

A) The time they last logged in.

B)

Answer 1

You can use a CASE statement in your COUNT:

SELECT A.UserID,
  COUNT(
    CASE WHEN TIME BETWEEN DATE_SUB( NOW( ) , INTERVAL 3 MONTH ) AND NOW( )
    THEN Activity
  END ) AS Logins,
  MAX( TIME ) AS LastLogin  
FROM UserMaster A  
LEFT JOIN UserWebActivity B ON A.UserID = B.UserID  
AND Activity =  'Login'  
GROUP BY A.UserID

This solution however will be less efficient than @MarkByers if you have a large amount of data.