Should I cast int to varchar?

denis_the_thief · August 16, 2017, 3:22pm

Someone asked me: When I insert an integer into a varchar column, SQL Server automatically converts it and there's no error. Should we cast it?

I thought it was good practice to cast the integer to a varchar but I couldn't come up with a good reason.

Thoughts?

gbritton · August 16, 2017, 3:30pm

One basic rule: Explicit is better than implicit. For that reason alone, I cast things rather than relying on implicit conversion

JamesK · August 16, 2017, 3:33pm

Another reason that explicit is better than implicit - to avoid errors such as what you will see if you run the following query:

CREATE TABLE #A( id VARCHAR(32));
INSERT INTO #A VALUES (1),('x'),(2);
DROP TABLE #A;

denis_the_thief · August 16, 2017, 3:38pm

JamesK:

Another reason that explicit is better than implicit - to avoid errors such as what you will see if you run the following query:
CREATE TABLE #A( id VARCHAR(32));
INSERT INTO #A VALUES (1),('x'),(2);
DROP TABLE #A;

Ahhh, good one