HOST_ID (Transact-SQL)

char(10)

When the parameter to a system function is optional, the current database, host computer, server user, or database user is assumed. Built-in functions must always be followed by parentheses.

System functions can be used in the select list, in the WHERE clause, and anywhere an expression is allowed.

The following example creates a table that uses HOST_ID() in a DEFAULT definition to record the terminal ID of computers that insert rows into a table recording orders.

CREATE TABLE Orders
   (OrderID     int       PRIMARY KEY,
    CustomerID  nchar(5)  REFERENCES Customers(CustomerID),
    TerminalID  char(8)   NOT NULL DEFAULT HOST_ID(),
    OrderDate   datetime  NOT NULL,
    ShipDate    datetime  NULL,
    ShipperID   int       NULL REFERENCES Shippers(ShipperID));
GO

Reference