Excel Query Using MariaDB ODBC Driver
I've figured out how to execute custom queries against MariaDB in Excel.


Create your DSN using the "ODBC Data Sources (32-bit)" desktop app and leave all options as the default, except the connection page settings and "Return matched rows instead of affected".
  
In Excel, on the sheet you want the query to show up on, on the data tab, select "From Other Sources" -> "From Data Connection Wizard".
  
In the dialog that pops up, select "ODBC DSN" and click "Next".
Find the DSN you created earlier and click "Next".
Now you need to select a table, just one. (We will change this later)
Click "Next", then "Finish", then "OK". The data from your table should populate the sheet, starting in what ever cell you specified before hitting that last "OK".


Okay, That's great! But how do I run a custom query with joins and a where clause? Read on my friend.


Select any cell in the table that resulted from the above steps.
In the design tab (should have opened when you clicked into the table) select the "Properties" button.
  
Click the "Connection Properties" button beside the "Name" field.
  
Now, on the "Definition" tab, in the "Command text:" field, you can paste in your query.
  


I've tested this with basic joins and where statements. Everything seemed to work fine, so this should be enough to get you started. I have not tested sub-queries or any other advanced features yet.