SQLServer IDENTITY Column with text

Question

In addition to the other answers, you could create a computed column on the table to provide what you are asking for.

CREATE TABLE dbo.MyTable
(
    Id int NOT NULL PRIMARY KEY,
    CombinedId AS 'ABCD-' + CAST(Id as varchar(16)) 
)

Or:

CREATE TABLE dbo.MyTable
(
    Id int NOT NULL PRIMARY KEY,
    PrefixField varchar(16),
    CombinedId AS PrefixField + CAST(Id as varchar(16)) 
)

(Your question doesn’t say whether the prefix is intended to be fixed or not…)