Design to represent employee check-in and check-out - mysql

Question

I currently have a table which represents the start and stop work times of an employee:
id_employee int
check_in datetime
check_out datetime
It requires an update on check_out when the employee is finished.
Would it be preferable to have a table as follows ?
id_employee int
date_event datetime
event_type varchar, values can be CHECKIN or CHECKOUT.
To determine if an employee has already checked in all I have to is check if the last record for a given employee has an event_type of CHECKIN. Also, fetching a record and updating it is no longer necessary.
Is the second approach better ? Or do you have other suggestions ?

Answer 1

I know this post is outdated but, this is for someone who's still looking for solution:
Attendance Table Structure
id | int
employee_code | varchar
status | enum('check_in','check_out')
created | datetime
Data
id employee_code status created
1 EMP0001 check_in 2016-08-20 09:30:30
2 EMP0001 check_out 2016-08-20 18:15:00
3 EMP0002 check_in 2016-08-21 14:52:48
4 EMP0002 check_out 2016-08-21 21:09:18
Query
SELECT
A1.employee_code,
A1.created AS check_in_at,
A2.created AS check_out_at,
TIMEDIFF(A2.created, A1.created) AS total_time
FROM
tbl_attendances AS A1
INNER JOIN tbl_attendances AS A2
ON A1.employee_code = A2.employee_code
AND DATE(A1.created) = DATE(A2.created)
WHERE 1 = 1
AND A1.status = 'check_in'
AND A2.status = 'check_out'
AND DATE(A1.created) BETWEEN '2016-08-20'
AND '2016-08-21'
AND DATE(A2.created) BETWEEN '2016-08-20'
AND '2016-08-21'
ORDER BY A1.created DESC
Results
employee_code check_in_at check_out_at total_time
EMP0002 2016-08-21 14:52:48 2016-08-21 21:09:18 06:16:30
EMP0001 2016-08-20 09:30:30 2016-08-20 18:15:00 08:44:30
For specific employee add AND A1.employee_code = 'EMP0001' in WHERE clause

Answer 2

As usual, "it depends".
Option 1 is easier to build, and simpler to query. Finding out who checked in but didn't check out is a simple query; finding the total hours worked for each employee is also straightforward. This simplicity probably means it will be faster for common queries. The only drawback I see is that it is harder to extend. If you want to capture a different event type for "lunch break", for instance, you have to add extra columns.
Option 2 is more flexible - you can add new event types without changing your schema. However, simple queries - how many hours did employee x work in June - are quite tricky. You pay for the flexibility in significant additional effort.
So, it depends what you mean by "better".

Answer 3

Format #2 is better because :
This table is just a punch record entry - Even if it has anomalies it doesn't matter.
Going forward this table will expand, for example you might want to introduce two more events INTERVAL_OUT, INTERVAL_IN. Second format will keep it simple.
If possible use event_type_id instead of event_type and another table event_type or just a constant array eg.
array_event_name = array (1=>CHECKIN, 2=>CHECKOUT, 3=>INTERVAL_IN, 4=>INTERVAL_OUT)

Answer 4

i would go with the second one.
however, the main questions and business rules will be the same and answerable by either approach.

Answer 5

Option #1
With the first option, the database itself can better protect itself from some anomalies1. Some anomalies are still possible2, but it's a start.
On the other hand, InnoDB tables are clustered and secondary indexes in clustered tables can be expensive (see the "Disadvantages of clustering" in this article), which is something to consider if you need to query on check_out.
Option #2
With the second option, you are relying on the imperative code even for anomalies that can be prevented purely declaratively with the database design.
On a plus side, you are less likely to need secondary indexes.
Choice
So in a nutshell, go with the first option, unless you need a secondary index. If you do need the secondary index, depending on what kind of index covering you wish to achieve, you might go with either option.
1 Such as checking-out without first checking-in.
2 Such as checking-in again, without first checking-out, overlapping "stints", etc...

Answer 6

I would go with the first option here. Putting both time stamps in a single row will enhance your search time and will make your calculations easier.
Suppose you want to calculation work hours for an employee for a day. Your search will stop at the first line it matches and you will have all the required data. You wont have to dig any deeper which is not the case with option 2. Option 1 also reduces your table size by using only 1 row per check-in/check-out.
Option 2 does have one advantage though. When checking out, your database will have to do a search to update the data for option 1. For option 2, its just a write.
Considering the fact that you will search the data more than once, you can give up the direct insert advantage to gain a better structure and faster search. Although the final choice is up to you.
Good Luck!