Recently, I received an interesting question from a reader who was migrating their database from MySQL to SQL Server. They were facing a unique situation where they had been using an Unsigned 64-bit integer in MySQL, but couldn’t find an appropriate datatype in SQL Server to migrate that column. Changing the datatype to VARCHAR(n) was not an ideal solution as it would lead to performance issues in the future.

After giving it some thought, I came up with a simple solution. The NUMERIC datatype in SQL Server can be used to store 64-bit unsigned integer values. By using NUMERIC(20), we can store the 64-bit unsigned integer, NUMERIC(10) for 32-bit unsigned integer, and NUMERIC(5) for 16-bit unsigned integer. The NUMERIC datatype supports a maximum precision of 38.

However, there are a few things to keep in mind when using the NUMERIC datatype. While it will accept the 64-bit unsigned integer, it will also allow negative values. To ensure that only positive integers are accepted, additional constraints need to be applied to the column.

Another concern is that SQL Server will store the number as numeric and treat it as a positive integer for all practical purposes. Therefore, it is necessary to write application logic to interpret it as a 64-bit unsigned integer.

If you are already using unsigned integers in your application, there is a good chance that you already have logic in place to handle them.

Overall, while SQL Server does not have a specific datatype for unsigned 64-bit integers, the NUMERIC datatype can be used as a workaround. By applying constraints and implementing proper application logic, it is possible to store and interpret these values effectively.