На ASP.NET это long a на MS Sql будет bigint

int, bigint, smallint, and tinyint
Exact number data types that use integer data.
bigint
Integer (whole number) data from -2^63 (-9,223,372,036,854,775,808) through 2^63-1 (9,223,372,036,854,775,807). Storage size is 8 bytes.
int
Integer (whole number) data from -2^31 (-2,147,483,648) through 2^31 - 1 (2,147,483,647). Storage size is 4 bytes. The SQL-92 synonym for int is integer.
smallint
Integer data from -2^15 (-32,768) through 2^15 - 1 (32,767). Storage size is 2 bytes.
tinyint
Integer data from 0 through 255. Storage size is 1 byte.