I went years without knowing how useful the Alt key was, it’s not well documented but I can guarantee that once you know about it and give it a little practice you won’t be able to live without it.
While I’m filing this under SSMS Tips and Tricks but it works equally in Visual Studio, VS Code, Azure Data Studio and even Notepad ++ (but not plain old vanilla notepad). It’s worth a test in other places too.
What does the Alt Key Do In SSMS?
Holding down the Alt allows you to select an arbitrary block in a text entry area. With that done you can act on the entire selection e.g. by typing, copying, or pasting.
My most common use is adding commas. Have you ever had a list of field names or values that you need to be comma separated? Perhaps you’ve used the Alt + F1 keyboard shortcut to list fields in a table and now you want them in a SELECT statement. Perhaps you have a list of row identifiers of test cases in a large data set that you want to drop into an IN operator so you can see the results. Whatever the need, at some point you’ve probably sat pressing the down arrow and comma key over and over thinking there must be an easier approach (I used to do this kind of stuff in Excel before I knew better).
With the Alt key you can just select every row and type your text into all of them at the same time. A picture is worth a thousand words so here’s an animated gif of the process in action.
How Does the Alt Key Affect Copying and Pasting?
Alt also allows you to vary how you copy and paste. A normal multi line copy in the clipboard combined with Alt to select multiple rows results in those multiple rows being pasted multiple times. Not often useful unless you want to generate a lot of lines of text quickly.
If you hold down the Alt key to select your copy area then the multiple select is remembered and it fills downward when pasting. Again, this is easier illustrated than described.
Putting It All Together
Once you understand the behaviour you can start to put this together to do something more advanced, this comes in handy where you need to apply the same function to multiple fields and then also need to give those fields unique names. It’s a common and tedious process without the Alt key. With it we can type on multiple lines at the same time for the function and then paste to multiple rows for the field name. The final process looks like this.
I couldn’t live without the Alt key now and after a bit of practice doing things like the above are now so embedded into my muscle memory they just happen as I write queries. It’s well worth the effort to get to that point in my opinion, I’m a big fan of anything that reduces a dull task to something quick.