🔥Now, let’s move to the next topic:

✅ SQL String Functions

🧠 1. What are String Functions?
String functions are used to
👉 manipulate text data
👉 clean messy data
👉 format outputs

Used heavily in:
✔ Data Analytics
✔ Reporting
✔ ETL processes

⚡ 2. Common String Functions
Function : Purpose
UPPER() : Convert to uppercase
LOWER() : Convert to lowercase
LENGTH() : Count characters
CONCAT() : Join strings
SUBSTRING() : Extract part of string
TRIM() : Remove spaces
REPLACE() : Replace text

🔥 3. UPPER() & LOWER()

SELECT UPPER(name) AS upper_name
FROM employees;

SELECT LOWER(name) AS lower_name
FROM employees;

🔥 4. LENGTH()
👉 Count number of characters

SELECT name, LENGTH(name) AS total_chars
FROM employees;

🔥 5. CONCAT()
👉 Combine strings

SELECT CONCAT(first_name, ' ', last_name) AS full_name
FROM employees;

🔥 6. SUBSTRING()
👉 Extract part of string
SELECT SUBSTRING(name, 1, 3)
FROM employees;

✔ Extracts first 3 characters

🔥 7. TRIM()
👉 Remove extra spaces
SELECT TRIM(' SQL ');

✔ Result → SQL

🔥 8. REPLACE()
👉 Replace text inside string

SELECT REPLACE('I love Java', 'Java', 'SQL');

✔ Result → I love SQL

🎯 9. Practice Tasks
1. Convert names to uppercase
2. Convert emails to lowercase
3. Combine first & last names
4. Extract first 4 letters of names
5. Remove extra spaces from city names

⚡ Mini Challenge 🔥
👉 Create employee usernames using:
first 3 letters of name + employee ID

Example:
Amit + 101 → Ami101

🔥 Mini Challenge Solution 💯

👉 Requirement:
Create username using:
• First 3 letters of name
• Employee ID

Example:
Amit + 101 → Ami101

✅ SQL Solution
SELECT name,
emp_id,
CONCAT(SUBSTRING(name, 1, 3), emp_id) AS username
FROM employees;

✅ Example Output
name : emp_id : username
Amit : 101 : Ami101
Neha : 102 : Neh102
Ravi : 103 : Rav103

🧠 How It Works
👉 SUBSTRING(name, 1, 3)
Extracts first 3 letters

👉 CONCAT()
Combines extracted text with employee ID

🔥 Real-World Usage:
String functions are commonly used for:
👉 Username generation
👉 Email formatting
👉 Data cleaning
👉 Customer IDs 💯

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