Added softcopy and queries for assignment a7.

Practical/Assignment-A7/Queries-A7.md

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+## Creating tables
+
+`Library` table:
+```sql
+CREATE TABLE Library(
+    id NUMBER(12),
+    title VARCHAR(255),
+    dateofissue DATE,
+    author VARCHAR(255)
+);
+
+```
+
+`Library_Audit` table:
+```sql
+CREATE TABLE Library_Audit(
+    id NUMBER(12),
+    title VARCHAR(255),
+    dateofaction DATE,
+    author VARCHAR(255),
+    status VARCHAR(255)
+);
+
+```
+
+## Inserting values
+
+`Library` table:
+```sql
+INSERT INTO Library VALUES (1, 'Berserk', TO_DATE('2024-07-28','YYYY-MM-DD'), 'Prashant');
+INSERT INTO Library VALUES (2, 'Dark', TO_DATE('2024-07-15','YYYY-MM-DD'), 'Rajendra');
+INSERT INTO Library VALUES (3, 'Hannibal', TO_DATE('2024-07-20','YYYY-MM-DD'), 'Manoj');
+INSERT INTO Library VALUES (4, 'AOT', TO_DATE('2024-07-30','YYYY-MM-DD'), 'Rajesh');
+INSERT INTO Library VALUES (5, 'GOT', TO_DATE('2024-07-19','YYYY-MM-DD'), 'Anil');
+
+```
+
+## Trigger
+
+```sql
+CREATE OR REPLACE TRIGGER library_action
+AFTER INSERT OR UPDATE OR DELETE ON Library
+FOR EACH ROW
+BEGIN
+	IF INSERTING THEN
+    	INSERT INTO Library_Audit (id, title, dateofaction, author, status) VALUES (:NEW.id, :NEW.title, current_timestamp, :NEW.author, 'Insert');
+	ELSIF UPDATING THEN
+        INSERT INTO Library_Audit (id, title, dateofaction, author, status) VALUES (:OLD.id, :OLD.title, current_timestamp, :OLD.author, 'Update');
+	ELSIF DELETING THEN
+        INSERT INTO Library_Audit (id, title, dateofaction, author, status) VALUES (:OLD.id, :OLD.title, current_timestamp, :OLD.author, 'Delete');
+	END IF;
+END;
+/
+
+```
+
+## Testing trigger
+
+### Insert operation
+
+```sql
+INSERT INTO Library VALUES (15, 'CREW', TO_DATE('2024-07-22','YYYY-MM-DD'), 'Ramesh');
+INSERT INTO Library VALUES (14, 'Ninteen Eighty Four', TO_DATE('2024-07-01','YYYY-MM-DD'), 'Omkar');
+
+SELECT * FROM Library;
+SELECT * FROM Library_Audit;
+
+```
+### Update operation
+
+```sql
+UPDATE Library SET id = 6, title = 'Sherlock', author = 'Deepak' where id = 3;
+UPDATE Library SET id = 7, title = 'MR. ROBOT', author = 'Varad' where id = 4;
+
+SELECT * FROM Library;
+SELECT * FROM Library_Audit;
+
+```
+
+### Delete operation
+
+```sql
+DELETE FROM Library WHERE id = 1;
+DELETE FROM Library WHERE id = 5;
+
+SELECT * FROM Library;
+SELECT * FROM Library_Audit;
+
+```
+
+---