Whats the username property in firedac

On Windows 10, local PC using firedac with mysql database.

I am not sure if the connection string should have
User_Name
or
UserName

Underscore didnt work, I tried without underscore and it still didnt work. I put both in. Its working.

Which one is it supposed to be?

You can do it more easily by using one of the overloaded methods of TFDConnection. There is one where the user name and password are supplied as string arguments so you don’t have to worry about underscores etc in the connection string and instead just let FireDAC take care of it for you.

Here’s an example from a working app. In my example the server and database are configurable so they are passed in as arguments - you could, of course put hardcoded values in there instead or make the whole thing configurable.

MyConnection1.Open(Format('DriverID=MySQL;Server=%s;Database=%s;Port=%d', [TheServer, TheDB, 3306]), 'yourusername', 'yourpassword');