Inconsistencies With SQL_VARIANT

Erik Darling warns against using SQL_VARIANT data types:

I half-stumbled on the weirdness around SQL_VARIANT a while back while writing another post about implicit conversion. What I didn’t get into at the time is that it can give you incorrect results.

When I see people using SQL_VARIANT, it’s often in dynamic SQL, when they don’t know what someone will pass in, or what they’ll compare it to. One issue with that is you’ll have to enclose most things in single quotes, in case a string or date is passed in. Ever try to hand SQL those without quotes? Bad news bears. You don’t get very far.

Read on for the demo.  I have never used SQL_VARIANT in any project.  I’ve done a lot of crazy things with SQL Server (some of them intentionally) but never this.

Related Posts

Using The ROWVERSION Type For ETL

Max Vernon shows us how to use the ROWVERSION data type to tell how much work you have to do to ETL data over from one table to another: The OLTP table implements a rowversion column that is automatically updated whenever a row is updated or inserted. The rowversion number is unique at the database level, and increments […]

Read More

VARCHAR Size And Memory Grant Estimates

Arthur Daniels shows us a good reason for using better data sizes than just VARCHAR(MAX) everywhere: That’s a lot of desired memory, 1,493,120 KB aka 1.4 GB, but there was only 25 MB used in the sort. So why was SQL Server so far off the right estimate? It’s the data types we picked. That’s a […]

Read More

Categories

March 2017
MTWTFSS
« Feb Apr »
 12345
6789101112
13141516171819
20212223242526
2728293031