SQL String Functions (Part 1)

String functions are used to manipulate text values stored in a database. These functions help convert letter cases, count characters, and extract specific parts of a string.

In this article, we will learn the following CBSE-prescribed SQL string functions:

• UPPER() / UCASE()
• LOWER() / LCASE()
• LENGTH()
• LEFT()
• RIGHT()

---

Sample Table

EmpID	Name	Department
101	Amit Sharma	Sales
102	Neha Gupta	Finance
103	Rohan Verma	HR

---

1. UPPER() / UCASE()

Syntax

UPPER(column_name)

OR

UCASE(column_name)

Example

SELECT UPPER(Name)
FROM Employee;

Output

AMIT SHARMA
NEHA GUPTA
ROHAN VERMA

---

2. LOWER() / LCASE()

Syntax

LOWER(column_name)

OR

LCASE(column_name)

Example

SELECT LOWER(Name)
FROM Employee;

Output

amit sharma
neha gupta
rohan verma

---

3. LENGTH()

Syntax

LENGTH(column_name)

Example

SELECT Name,
       LENGTH(Name)
FROM Employee;

If the name is "Amit Sharma", the result includes the space between the two words.

---

4. LEFT()

Syntax

LEFT(string, number_of_characters)

Example

SELECT LEFT(Name,4)
FROM Employee;

Output

Amit
Neha
Roha

---

5. RIGHT()

Syntax

RIGHT(string, number_of_characters)

Example

SELECT RIGHT(Name,6)
FROM Employee;

Output

Sharma
Gupta
Verma

---

Comparison of String Functions

Function	Purpose	Example
UPPER()	Convert to uppercase	UPPER('amit')
LOWER()	Convert to lowercase	LOWER('AMIT')
LENGTH()	Count characters	LENGTH('Python')
LEFT()	Extract left characters	LEFT('Python',3)
RIGHT()	Extract right characters	RIGHT('Python',3)

---

Real-Life Applications

Function	Application
UPPER()	Generate reports in uppercase.
LOWER()	Standardize email addresses.
LENGTH()	Validate passwords or IDs.
LEFT()	Extract state or branch codes.
RIGHT()	Extract last digits of account numbers.

---

Common Errors

Error	Reason
Unknown Column	Incorrect column name.
Syntax Error	Missing brackets or commas.
Incorrect Arguments	Wrong number of parameters.

---

Quick Revision

Function	Purpose
UPPER()	Uppercase
LOWER()	Lowercase
LENGTH()	Count characters
LEFT()	Characters from left
RIGHT()	Characters from right

---

CBSE Exam Tips

• UPPER() and UCASE() perform the same function.
• LOWER() and LCASE() perform the same function.
• LENGTH() counts spaces as characters.
• LEFT() extracts characters from the beginning of a string.
• RIGHT() extracts characters from the end of a string.

---

Summary

SQL string functions help manipulate text stored in database tables. Functions such as UPPER(), LOWER(), LENGTH(), LEFT(), and RIGHT() are commonly used for formatting, validating, and extracting text data. These functions are frequently used in CBSE theory questions, practical examinations, and real-world database applications.