This script will find all columns in a table that have only 1 value. If a column only has 1 value for all rows it probably isn't being used and is causing technical debt. Consider removing unneeded columns.
Understanding Column Properties for a SQL Server Table
Designing a table can be a little complicated if you don’t have the correct knowledge of data types, relationships, and even column properties. In this tip, Brady Upton goes over the column properties and provides examples.