Baizeed Rony Academy

04/08/2025

Good night

31/07/2025

How to make Progress Bar In Oracle Apex!

24/07/2025

🔗 FOREIGN KEY with ON DELETE Options
When you define a foreign key, you can specify what should happen to the child table rows when a row in the parent table is deleted.

🧨 1. ON DELETE CASCADE
👉 Automatically deletes matching rows in the child table when the parent row is deleted.

🧯 2. ON DELETE SET NULL
👉 Automatically sets the foreign key column(s) in the child table to NULL when the parent row is deleted.

✅ Example Scenario
Let’s say we have:

A parent table: departments

A child table: employees (each employee belongs to a department)

🔧 Step-by-Step SQL Example:
🔹 Step 1: Create Parent Table

CREATE TABLE departments (
dept_id NUMBER PRIMARY KEY,
dept_name VARCHAR2(100)
);

🔹 Step 2: Create Child Table with ON DELETE CASCADE
CREATE TABLE employees (
emp_id NUMBER PRIMARY KEY,
emp_name VARCHAR2(100),
dept_id NUMBER,
CONSTRAINT emp_dept_fk FOREIGN KEY (dept_id)
REFERENCES departments(dept_id)
ON DELETE CASCADE
);

✅ Now if you delete a row from departments, all related rows in employees will be deleted automatically.

🔹 Step 3: Create Child Table with ON DELETE SET NULL
If instead, you want to keep the employee, but set dept_id to NULL when the department is deleted:

CREATE TABLE employees (
emp_id NUMBER PRIMARY KEY,
emp_name VARCHAR2(100),
dept_id NUMBER,
CONSTRAINT emp_dept_fk FOREIGN KEY (dept_id)
REFERENCES departments(dept_id)
ON DELETE SET NULL
);

✅ Now when a department is deleted, affected employees’ dept_id will become NULL.

🔍 Visual Summary:
Option Result when parent row is deleted
ON DELETE CASCADE Deletes matching child rows
ON DELETE SET NULL Sets foreign key column(s) in child to NULL

23/07/2025

Good Morning

20/07/2025

Shout out to my newest followers! Excited to have you onboard! Hina Khan, Mohamed Elsayed

18/07/2025

In Oracle SQL, both CASE and DECODE are used for conditional logic, but DECODE is specific to Oracle syntax, while CASE is part of the ANSI SQL standard.

✅ DECODE – Oracle-specific

Proprietary to Oracle (not standard SQL).

Simpler syntax for equality checks.

Only works with equality conditions (can't do >, ,

18/07/2025

17/07/2025

Let's start the training today.

17/07/2025

🔶 Some Powerful Oracle-Supplied Packages Every Developer Should Know! 🔶
Oracle provides a wide range of built-in PL/SQL packages to extend functionality, automate processes, and manage tasks more efficiently.

🚀 Here are some essential Oracle-Supplied Packages:

📦 DBMS_OUTPUT – Display output from PL/SQL programs (for debugging).

📂 UTL_FILE – Read/write files from the database server.

📧 UTL_MAIL – Send emails directly from PL/SQL (SMTP support).

📢 DBMS_ALERT – Enables asynchronous communication between sessions.

🔐 DBMS_LOCK – Provides user-defined locking mechanisms.

👤 DBMS_SESSION – Control and manage user sessions.

📊 DBMS_APPLICATION_INFO – Track module, action, and client info for performance tuning.

🌐 HTP – Generate HTML content using PL/SQL (used in Oracle Web Toolkit).

⏰ DBMS_SCHEDULER – Automate jobs, scheduling PL/SQL procedures and scripts.

💡 Mastering these packages can boost your productivity, improve automation, and make your Oracle applications smarter!

17/07/2025