How do you insert null values into SQL Server

Managing potential "NULL headaches"

To handle NULL values in different scenarios, consider the ISNULL() function. This nifty tool allows you to replace any NULL value with a default, ensuring a successful data insertion:

INSERT INTO TableName (Column1, Column2) 
VALUES (ISNULL(PossibleNullValue, 'Default'), 'CertainValue'); 
-- Are they NULL or not? Who knows? SQL Server does, there is no NULLophobia here!
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Overriding defaults and setting nullable columns

For columns with default values, you can take aim at overriding them by either omitting the column during the insert statement or detailing NULL explicitly:

CREATE TABLE MyTable (ID int NOT NULL, Data varchar(255) NULL DEFAULT 'N/A');
-- Now we can have our cake (default value) and eat it too (explicit NULL)
INSERT INTO MyTable (ID) VALUES (1); -- 'Data' would fall back to default ('N/A')
INSERT INTO MyTable (ID, Data) VALUES (2, NULL); -- 'Data' is deliberately set to NULL
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The secret art of NULL insertion: Advanced tactics

Before you go wild inserting NULLs everywhere, let's discuss some additional considerations:

The allowance of NULLs

Ensure the column accepts NULLs. Inserting a NULL into a non-nullable column is like fitting a square peg into a round hole - unlikely and error-prone.

Foreign keys limitations

Almost forgot, foreign keys allow NULLs only if the constraint explicitly allows it. It's like a diplomatic agreement; certain protocols need to be followed.

Importance of Transaction Integrity

Mark correct transaction integrity when inserting NULLs. Use transactions to ensure all changes are valid or can be easily rollbacked.

NULLs impact on indexes

And last but not least,indices. How NULLs impact your indexes can frustrate or fascinate you, depending on constrained, filtered, or unique ones. Up to you!