Odd Behavior With Altering Columns

Kevin Feasel

2019-01-16

Syntax

Solomon Rutzky points out a few things which you can unintentionally change when running an ALTER TABLE [tbl] ALTER COLUMN [col] command:

If the column is NOT NULL, then not specifying NOT NULL will cause it to become NULLable. The documentation for ALTER TABLE even states:

ANSI_NULL defaults are always on for ALTER COLUMN; if not specified, the column is nullable.

Let’s see for ourselves. 

Solomon also has a couple collation-related items, including unexpected silent truncation when working with UTF-8 collations.

Related Posts

COUNT And NULL

Bert Wagner explains some of the trickiness of COUNT and NULL values in SQL Server: One thing I see fairly often (and am occasionally guilty of myself) is using COUNT(DISTINCT) and DISTINCT interchangeably to get an idea of the number of unique values in a column. While they will sometimes give you the same results, […]

Read More

Fun With QUOTENAME

Louis Davidson shares some tips on using the QUOTENAME function: Or if you are Rob Volk (@sql_r on Twitter), and you want to create an annoying database on your best frenemy’s SQL Server that includes brackets in the name, like: This [database] Is Awesome You will need to do: CREATE DATABASE [This [database]] Is Awesome]; […]

Read More

Categories

January 2019
MTWTFSS
« Dec Feb »
 123456
78910111213
14151617181920
21222324252627
28293031