In sql there are many options to generate unique number. Here I am explaining about how to generate standard unique number in sql. Below is sql query : CREATE TABLE dbo.tblTable1   (ID INT IDENTITY(1,1) NOT NULL PRIMARY KEY CLUSTERED,    UserID AS UID + RIGHT(00000000 + CAST(ID AS VARCHAR(8)), 8) PERSISTED,    username varchar(200),city varchar(200)   )