Question

This might be a stupid question. I need to have a Id field in a table. This Id is not a key (primary or whatever). The requirement says that user can input 10 digits in this field from the UI. This Id has no relation as of now with any otehr object in the system. Do you think If one can use nvarchar or bigint for this field. Does bigint would be an overhead for this purpose?

Answer 1

If you will ever perform any mathematical work with this column, then obviously an integral type is to be preferred. Alternatively, if this is a pure, opaque identifier, then a char or varchar column would seem to make more sense. And if leading zeros might be important, then obviously the integral types will not work, e.g. if storing a UK phone number, 01234 567890, you’d want that in a char column.

Edit and for bonus points, if it is an id that should always be ten digits:

CREATE TABLE T (
    /* Other columns */
    Id char(10),
    constraint CK_ID_Valid CHECK (LEN(ID)=10 and not ID like '%[^0-9]%')
)