Added queries to calculate the area of circle.

Practical/Assignment-A4+A5/Queries-A5.md

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+# Queries for Assignment-A5
+
+> [!NOTE]
+> Problem Statment: Write a PL/SQL code block to calculate the area of a circle for a value of radius varying from 5 to 9. Store the radius and the corresponding values of calculated area in an empty table named areas, consisting of two columns, radius and area.
+> Note: Instructor will frame the problem statement for writing PL/SQL block in line with above statement.
+
+## Creating table
+
+```sql
+CREATE TABLE areas (
+  radius INT NOT NULL,
+  area INT
+);
+
+```
+
+## Procedure
+
+```sql
+DECLARE
+  v_radius NUMBER; -- specify radius here since Live SQL cannot take input from user
+  -- Eg. v_radius NUMBER := 5 will take radius 5 as input
+  calcedArea NUMBER;
+  invalidData EXCEPTION;
+  psError EXCEPTION;
+
+BEGIN
+  -- if radius is less than 0, raise exception
+  IF (v_radius < 0) THEN
+    RAISE invalidData;
+  ELSIF (v_radius NOT BETWEEN 5 AND 9) THEN
+    RAISE psError;
+  END IF;
+
+  -- calc area
+  calcedArea := 3.14 * v_radius * v_radius;
+  DBMS_OUTPUT.PUT_LINE('For radius ' || v_radius || ' cm, the area is ' || calcedArea || ' sq. cm.');
+
+  -- add data to table
+  INSERT INTO areas VALUES (v_radius, calcedArea);
+  DBMS_OUTPUT.PUT_LINE('Inserted values to areas database.');
+
+EXCEPTION
+  WHEN invalidData THEN
+    DBMS_OUTPUT.PUT_LINE('Radius cannot be less than 0 cms. Please enter a valid value.');
+  WHEN psError THEN
+    DBMS_OUTPUT.PUT_LINE('Problem statement requires the radius to be between 5 and 9 cms.');
+  WHEN OTHERS THEN
+    DBMS_OUTPUT.PUT_LINE('An error occured. Error: ' || SQLERRM);
+
+END;
+/
+
+```