Why doesn't SQL Server support unsigned datatype?

Extending Identity column Range

Normal INT identity column in SQL Server gets maxed out at 2,147,483,647. But with the cunning usage of negative seed values we can approximately efface that:

CREATE TABLE MyTable (
    ID INT IDENTITY(-2147483648, 1), -- Starts from "Mirror World" INT to access 'double' the range
    ...
)


Here we are essentially scooping out every available integer from -2,147,483,648 to 2,147,483,647, thereby maximizing our value range.

Consider Bigger Types for larger Numbers

When enormous numbers are required, BIGINT might fall short. In these scenarios, DECIMAL(38, 0) becomes your trusty sidekick, catering to your need for larger numbers.

Refactoring for Negative Numbers

Refactoring the code can be an easier workaround than actual unsigned types. Supporting negative numbers might feel gargantuan, but in practice it allows us to adhere to the standard while concisely bypassing the limitations.

The Equivalence of the Unequivalent

Unsigned and Signed integers are functionally equivalent in representing a range of values. The balance of power between positives and negatives is your trade-off when planning your databases.

Implicit vs Explicit Conversions

Minimize surprises in your code by explicitly handling type conversions. This practice guards against unexpected overflow issues or implicit type casting errors. SQL Server's tactic of excluding unsigned types is to simplify the data type management by avoiding type proliferation.

Anticipating SQL Server's Limitations

BigInt and Decimal to the Rescue

Got numbers exceeding INT limit of 2^31-1? Say hello to BIGINT, capable of accommodating numbers till 2^63-1. Continue to DECIMAL(38, 0) for storage beyond, at the cost of lost non-integer performance.

Other Database Management Systems

The absence of unsigned integers in SQL Server doesn't equate their universal absence. Peers like MySQL support these types, inviting complexity in type systems but offering more options.

Responses from Microsoft

SQL Server's stance on the issue is brought to light by Microsoft's previous discussions and feedback. Their "Won't Fix" approach in response to public requests for unsigned integers underscores SQL Server's roadmap on certain types.

Practical Utility

As a database designer, it is crucial to make shrewd choices on data types. If the range of ID columns hitting maximum values is getting you down, you might want to start with negative identity seed values.