TRY_PARSE Limitations: #SQLNewBlogger

I got a notification from a question I’d posted at SQL Server Central: Getting the Average. A user had posted their repro didn’t work, with no real comment. As a SQLNewBlogger FYI, that type of post shows poor communication and a lack of communication. I see that a lot and it’s a challenge in the modern world.

Another post for me that is simple and hopefully serves as an example for people trying to get blogging as #SQLNewBloggers.

A Quick Setup

This was what the user posted:

declare @t table
(
    id int identity
  , i int
);

insert @t
select null;

insert @t
select 11;

select avg(try_parse(i as int))
from @t
group by id;

This does return an error, as you can see below.

Why?

Well, the TRY_PARSE() docs give part of an explanation. I highlighted this in Yellow, but the relevant text says “only for converting strings”.

Shouldn’t an int convert to a string? No, the precedence rules have int higher than char types. We convert lower to higher, not higher to lower.

SQLNewBlogger

I noticed something, thought for a second why this wouldn’t work, and then checked the docs. I decided to write this up and it was a 5-10 minute post for me. Easy to do and showcasing knowledge.

It helps me remember, might teach someone something, and gives an interviewer something to ask me. Add to your blog with short posts like this (or drop on LinkedIn).