MySql : Get data from two tables

Question

I am stuck with mysql query.Not able to proceed.

I have 2 tables where user's login time is recorded.Login time should be considered when either of the table contains entry. I want to find userwise sum of logins for a month.

I could reach till here. But not able to understand how to get sum

select table1.employeeId
     , date(table1.loginTime) as date1
     , date(table2.loginTime) as date2 
  from table1 
     inner join table2 on table1.employeeId=table2.employeeId 
                      and table1.loginTime>='2017-01-01 00:00:00' 
                      and table1.loginTime<='2017-01-31 23:59:59' 
                      and table2.loginTime>='2017-01-01 00:00:00' 
                      and table2.loginTime<='2017-01-31 23:59:59'

For ex : count=0 employe1 logged
on 1-Jan-2017 in table1 & table2 <- count++ (if he logs in 2 tables then only 1 count should be considered)

on 2-Jan-2017 in table1 <- count++

So for employee1 count is 2

Answer 1

You could do this with outer joins, but it would be needlessly complex:

select employeeId
     , count(*) as loginCount
from ( select employeeId
            , loginTime
         from table1
        where loginTime between '2017-01-01 00:00:00' 
                            and '2017-01-31 23:59:59'
       union
       select employeeId
            , loginTime
         from table2
        where loginTime between '2017-01-01 00:00:00' 
                            and '2017-01-31 23:59:59'
      ( as a
group by employeeId; 

Answer 2

Another approach:

    SELECT
    employeeId,
    COUNT(1)+
    (
     SELECT COUNT(1)
      FROM TABLE2 T2
      WHERE MONTH(T2.loginTime) = 1
      AND YEAR(T2.loginTime) = 2017
      AND T2.employeeId = T1.employeeId
    )
    AS LOGINTIMES
    FROM
    TABLE1 T1
    WHERE MONTH(loginTime) = 1
    AND YEAR(loginTime) = 2017
    GROUP BY employeeId

Sample fiddle: http://sqlfiddle.com/#!9/45ce27/3/0