EMP Columns Datatype Size Constraints E_ID Number 3 Primary key E Name Varchar2 15 D_ID Varchar2 3 Foreign key Salary Number 8,2 name a Write a SQL query to add constraint UNIQUE to the column Salary with a suitable constraint (1.5 Marks) b Write an SQL query to remove the table from the database. (1Mark) ED 222 333 444 555 E Name Ahmed Safa Ahmed Safa EMP D D D10 D20 D30 D10 Salary 200.65 300.50 400.00 Write an SQL query to change employee name "Ahmed" as "Mohamed" whose department ID is D10