A NULL in the CREATE TABLE statement specifies that a special value called NULL (which usually represents unknown or not applicable values) is allowed in the column. These values differ from all other values in a database.
Can we use NULL in WHERE clause?
Generally, NULL data represents data does not exist or missing data or unknown data. IS NULL & IS NOT NULL in SQL is used with a WHERE clause in SELECT, UPDATE and DELETE statements/queries to validate whether column has some value or data does not exist for that column. Please note that NULL and 0 are not same.
How do I allow nulls in SQL?
How to Change a Column to Allow NULL in MS SQL Server
- First, specify the name of the table from which you want to change the column.
- Second, specify the column name with size which you want to change to allow NULL and then write NULL statement .
