如何在 MySQL 中将日历表与另外 2 个表进行内部连接

Question

I have 2 tables that I have to inner join in PHP MySQL but I can't really understand the syntax on inner join SQL syntax. This are the structure of the 2 tables:

attendance = EmpID, Date, TimeIn, LunchOut, LunchIn, TimeOut
actualot = EmpID, Date, TimeIn, TimeOut, Overtime

I need to join them in calendar table so that the missing dates will be seen also, this is my expected result:

result = Date, TimeIn, LunchOut, LunchIn, TimeOut, Overtime

Where date will be taken from calendar that should be equals to date of attendance with a given range like 2015-08-01 to 2015-08-30 and the Overtime is euqal to the id of attendance while the attendance is eual to the id of a given user id like 01450015. Note that i put each a auto increment primary key and the only related to each of them was the empid that is not a unique or primary key.

Answer 1

This is an example based on having a Calendar table:

SELECT C.Date, <additional columns>
FROM Calendar C LEFT OUTER JOIN
Attendance D ON C.Date = D.Date LEFT OUTER JOIN
ActualOT A ON D.EmpID = A.EmpID