👉Practice: Choose Right SQL Data Types

🧪 Practice: Define Appropriate SQL Data Types

Practice selecting the most suitable SQL data types for each column based on its purpose. Think about performance, storage, and real-world usage in a Bangladeshi context.

📋 Example 1: Employee Table

Column	Description	Best Data Type	Why?
emp_id	Employee ID (unique)	NUMBER	Used for indexing, numeric comparison is fast
name	Employee’s full name (Bangla)	NVARCHAR2(100)	Supports Bangla characters efficiently
gender	'M' or 'F'	CHAR(1)	Fixed length for single-character flag
salary	Monthly salary in BDT	NUMBER(8,2)	Handles decimal values with precision
hire_date	Date of joining	DATE	Standard date format
created_at	Exact entry timestamp	TIMESTAMP	Includes time & fractions of a second

📦 Example 2: Delivery System

Column	Description	Best Data Type	Why?
package_id	Unique tracking ID	VARCHAR2(20)	May include letters (e.g., BD12345)
destination	Address (Bangla)	NVARCHAR2(200)	Supports Unicode for addresses in Bangla
delivery_time	Duration taken to deliver	INTERVAL DAY TO SECOND	Measures time between dispatch and delivery
status	Delivered, Pending, Failed	VARCHAR2(20)	Variable-length status strings

📝 Your Turn (Practice)

Choose the best data type for each column:

1. student_name: Bangla names with variable length
2. student_id: Numeric ID
3. birth_date: Date of birth
4. blood_group: 'A+', 'O-', etc.
5. total_fee: Payable amount (BDT)
6. payment_status: Paid / Unpaid / Partial

👉 Try to answer on your own, then scroll to see suggestions:

✅ Suggested Types:

• student_name → NVARCHAR2(100)