The column exhibits the same behavior as a single timestamp column in a table with no other timestamp columns.

On initialization places a zero in that column, on future updates puts the current value of the timestamp in.

A default value is used on initialization, a current timestamp is inserted on update of the row.

A single table can't have two primary keys.it can only forgein keys.but u can use any number of foregin key in a single table.
Its impossible to create two primary key in a single table but if we use composite key we have do it just like that
CREATE TABLE Test (id1 INT NOT NULL, id2 INT NOT NULL, name CHAR(20) NOT NULL, PRIMARY KEY(id1,id2));

SELECT MAX(salary) FROM TRY
WHERE salary NOT IN(SELECT MAX(salary) FROM TRY)

Type the command EXEC_msver in the query analyzer and then press either F5 or click the green triangle on the analyzer.

Select Name,Salary from table1 where Salary =(select max(Salary) from table1)
UNION
Select Name,Salary from table1 where Salary =(select min(Salary) from table1)