Question

I am not good in sql. I am just trying to clear my doubts with you. Can i assign two constraints to single column.

e.g

     eno ename address mobileno
      1   A      US      9089877878
      2   B      UK      NULL
      3   C      IND     9089877878

Consider above example, I don’t want to allow user to enter NULL or same value for mobileno column. How can i restrict user to doing this??

Thanks for your important time.

Answer 1

CREATE TABLE table_name (column_name type NOT NULL,
UNIQUE (column_name))