Question: have this on my database

```
InspectionID  Inspection Date OdometerReading Truck Id
     1         2013-04-07       1000              1
     2         2013-04-14       2040              1
     3         2013-04-21       3000              1
    ...          .....          ....
     21         2013-05-23      1000              2
     22         2013-05-30      2000              2
     23         2013-06-07      3000              2
     24        2013-07-14       2040              3
     25         2013-07-21       3000             3
    ...          .....          ....             ....
     30         2014-05-23      15050             3
     34         2014-05-30      16032             1

```

I have selected DateStart: 2013-04-01 and DateFinished: 2014-06-01 on my datepicker, the query that should be selected is 2013-04-07 and 2014-05-30.

To summarize my question: How could i Select the First and Last Row between the Date Start and DateFinished Query so I can compute the average OdometerReading of each truck\_id on a specific time period

Answer: 
An underscore denotes the fact that you need to set a variable, but you do not plan on using the variable in the future. Instead of giving it an elaborate name, an underscore will be more simple and less clutter, especially in the case that the variable name doesn't matter. (since you do not use it again.)
If I'm not mistaken this carried over from Objective-C. When you did not "use" your pointer at all in the app, you would get a warning. In Swift 2 I believe they tried to implement something similar.