从两个表中选择并设置空列

Question

I have two tables

Schedule:

scheduleID    DriverID      ScheduleDate
11            1             2015-05-20
22            2             2015-05-20
33            NULL          2015-05-21
44            NULL          2015-05-21

and

Employee:

ID           Fname          Lname
1            jack           miller
2            kelly          moore
3            mark           sam
4            tom            hanks

I want to select from these two tables based on ScheduleDate and show the driver full name from Employee table and show null columns.

The result should be like:

scheduleID    Fname       Lname
33            NULL         NULL
44            NULL         NULL

I used:

select  row_number() over (order by scheduleID desc) as schedule, scheduleID, Driver_ID,FirstName,LastName
From Schedule, Employee
where scheduleDate= '2015-05-21' AND EmployeID=Driver_ID;

It works well if " scheduleDate= '2015-05-20' "

but I need to show null Columns too! any help!

Answer 1

You need a left join for this -- just emphasizing why you should never using implicit join syntax. Simple rule: Always use explicit join syntax. Never use commas in the from clause.

select row_number() over (order by scheduleID desc) as schedule, scheduleID, 
       Driver_ID, FirstName, LastName
From Schedule left join
     Employee
     on EmployeID = Driver_ID
where scheduleDate = '2015-05-21';