Question

SQL command for the following queries​

Answer 1

(i) The primary and foreign keys  could be:

• Doctors - DocID
• Patients - Pat_no

(ii) Update Patients set Department = 'OPD' where PatName = 'Neeraj';

(iii) Select DocName from Doctors where Department = 'ENT';

(iv) Update Patients set PatName = 'Raju' where Fee = '100';

(v) Update Doctors set Department = Null where Department = 'ENT';

• A primary key is a key that uniquely identified records in a table. It prevents the addition of duplicate values.
• A foreign key is a key that is a primary key in reference to another table.
• The 'Update' command is a DML command used to make changes to the data in the table.
• The 'Select' command is used to retrieve data from a table.