In this tutorial we’ll examine the important safety precautions necessary when altering existing data in a column, prior to actually issuing any ALTER commands that would potentially cause harm to the table itself. Understanding the Limitations of Data in NOT NULL ColumnsĬhanging the data structure of a column in SQL Server from NULL to NOT NULL, thereby disallowing non-null values in that column, is generally performed using the relatively simple ALTER TABLE syntax to appropriately change the column in question.
