Added P10 trigger (plsql). Engineered by Macho.

Practical/Practical Exam/PL-SQL/P10 - Trigger.md

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+# P10 - Trigger
+
+**Problem Statement:** Trigger: Write a after trigger for Insert, update and delete event considering following requirement:
+Emp(Emp_no, Emp_name, Emp_salary)
+a) Trigger should be initiated when salary tried to be inserted is less than Rs.50,000/-
+b) Trigger should be initiated when salary tried to be updated for value less than Rs. 50,000/-
+Also the new values expected to be inserted will be stored in new table Tracking(Emp_no,Emp_salary).
+
+---
+
+## Creating tables:
+```sql
+CREATE TABLE Emp(
+    Emp_no NUMBER(14),
+    Emp_name VARCHAR(255),
+    Emp_salary NUMBER(14)
+);
+
+CREATE TABLE Tracking(
+    Emp_no NUMBER(14),
+    Emp_salary NUMBER(14)
+);
+
+```
+
+## Trigger
+```sql
+CREATE OR REPLACE TRIGGER P10
+AFTER INSERT OR UPDATE ON Emp
+FOR EACH ROW
+BEGIN
+	IF inserting THEN
+		IF (:New.Emp_salary < 50000) THEN
+			insert into Tracking (Emp_no, Emp_salary) VALUES (:New.Emp_no, :New.Emp_salary);
+			DBMS_OUTPUT.PUT_LINE('Inserting record with salary < 50000');
+		END IF;
+	ELSIF updating THEN
+		IF (:New.Emp_salary < 50000) THEN
+			UPDATE Tracking SET Emp_salary = :New.Emp_salary WHERE Emp_no = :Old.Emp_no;
+			DBMS_OUTPUT.PUT_LINE('Updated value of salary < 50000 for a record');
+		END IF;
+	END IF;
+END;
+/
+
+```
+
+1. After performing insertion operation:
+```sql
+INSERT INTO Emp VALUES (1, 'Tanmay', 45000);
+INSERT INTO Emp VALUES (2, 'Rajesh', 35000);
+
+```
+
+<details>
+  <summary>Output</summary>
+  1 row(s) inserted.<br>
+  Inserting record with salary < 50000<br>
+<br>
+  1 row(s) inserted.<br>
+  Inserting record with salary < 50000<br>
+<br>
+  Tracking:<br>
+  EMP_NO	EMP_SALARY<br>
+  1	45000<br>
+  2	35000<br>
+
+</details>
+
+2. After performing update operation:
+```sql
+UPDATE Emp SET Emp_salary = 43000 WHERE Emp_no = 1;
+
+```
+<details>
+  <summary>Output</summary>
+  1 row(s) updated.<br>
+  Updated value of salary < 50000 for a record<br>
+  <br>
+  Tracking:<br>
+  EMP_NO	EMP_SALARY<br>
+  1	43000<br>
+  2	35000<br>
+
+</details>
+
+---