Q.Write SQL statements to

This tests UPDATE and DELETE, both of which need a WHERE clause to act on the right rows only.

Both of these are DML operations, and both need a WHERE clause so that they affect only the intended row.

(i) Changing data uses UPDATE ... SET ... WHERE. To set the marks of the student whose RollNo is 1 to 80:

UPDATE Student
SET Marks = 80
WHERE RollNo = 1;

The WHERE RollNo = 1 part is essential — without it, the marks of every student would be changed to 80.

(ii) Removing data uses DELETE FROM ... WHERE. To delete the record of the student whose RollNo is 2:

DELETE FROM Student
WHERE RollNo = 2;
``` …

The most dangerous mistake is leaving out the WHERE clause: 'UPDATE Student SET Marks = 80;' changes every row, and 'DELETE FROM Student;' empties the whole table. Also do not confuse D …