Formulas inside of Power Apps are very similar to Excel, for example, in Power Apps, the sum function allows me to sum a table of data. Here are some examples of other common use cases for formulas. It is very rare, that an app will need to just show all of the items inside of a list. More often than not, the data will need to be filtered. As you might guess, the function called filter, would do just that. If I select to this gallery, and the items or data source property, I can apply this function to filter the data in many different ways.

In my example, Employee Lists, there is a field called department. Let's filter this list so that it's only showing the employees in the sales department. To do that, I'll say filter, then you can see the function is wanting a data source or table to filter. I'll leave this as EmployeeList, I'll put a comma, and then here's where I will put my filter or logical test. Essentially, this next part of the function is what the filter will be, and what the function will use to evaluate each item in the list so that it knows whether or not to include it. I'll put department and an equal sign, and then in quotation marks, I'll put sales. Lastly, I'll put a close parentheses to close the function. Now I'm only seeing the employees, where the department field is set to sales.

Another common function is the user function. Power Apps has the capability, through this function, to gather some information, about the logged in user. Let's say we want to show a welcome message including the name of the currently logged in user. To do this, we'll add in a label. Inside of this label, we'll say, welcome, leaving a space at the end there, then we'll add an and, and now we'll say user, open parentheses, close parentheses. Notice how this function requires no input. However, this function is bringing back multiple things. If I had a period, you can see in this dropdown, that the function is getting the users name, email and image. We of course just want the name, so we'll select full name, and there we go.

The last function I'll show is the set function. This function sets what is called a global variable. The different variables in Power Apps will be covered in more detail and other courses. But for now, know that variables are used, to temporarily store data and to help applications be more efficient. If I were to use the user function, multiple times inside of this app, for example, it would cause the app to slow down because that function has to run every time that it is used to go and get the user's information. So, instead of slowing down our app, let's get the user's information one time, and store it inside of a variable. That way, each time we need the user's information, we don't have to slow down the app anymore, and can simply reference the variable. To do this, we'll go to our tree view and select app, this is where we can run formulas when app is first started. We'll say set, and we'll call our variable, varUser, and then put our user function.

Now, going back to our label, we can simply change user.full name, to varUser.full name. To actually set this variable, we'll click the ellipses, and hit run on start. Now you can see that the variable has been set, and we can see welcome Ben Fethers. We can of course, identify many other use cases for formulas or functions. Microsoft provides a list of all of the available formulas that can be used inside of Power Apps, as well as examples and how to use them. Go to https://docs.microsoft.com/en-us/powerapps/maker/canvas-apps/formula-reference to view the list.

In the next lecture, We'll cover combining multiple data sources.