Understanding Oracle SQL vs. PL/SQL: Key Differences

Oracle Database is widely used for managing and processing structured data. While working with Oracle, you often come across two key terms: SQL (Structured Query Language) and PL/SQL (Procedural Language/SQL). Although both are used for database interactions, they serve different purposes.

In this blog, we’ll explore the differences between Oracle SQL and PL/SQL, their use cases, and when to use each.

What is SQL in Oracle?

SQL (Structured Query Language) is a standard language used to interact with relational databases, including Oracle Database. It is used to perform operations like retrieving, inserting, updating, and deleting data from tables.

Key Features of SQL:

• Used for data retrieval and manipulation
• Works with DML (Data Manipulation Language) and DDL (Data Definition Language)
• A declarative language (you specify what to do, not how to do it)
• Single SQL statement execution (not procedural)

Example SQL Queries:

• Retrieve all employees from the database:

SELECT * FROM Employees;

• Insert a new employee record:

INSERT INTO Employees (EmployeeID, Name, Department, Salary)  
VALUES (101, 'Shrinivas Baddi', 'IT', 22000);

• Update salary for an employee:

UPDATE Employees  
SET Salary = 80000 
WHERE EmployeeID = 101;

• Delete an employee record:

DELETE FROM Employees WHERE EmployeeID = 101;

What is PL/SQL in Oracle?

PL/SQL (Procedural Language/SQL) is an extension of SQL that allows procedural programming features like loops, conditions, and error handling inside Oracle Database. It is used to create functions, stored procedures, triggers, and blocks of code that execute multiple SQL statements at once.

Key Features of PL/SQL:

• Procedural language (allows variables, loops, and conditional statements)
• Supports error handling (EXCEPTION handling)
• Can be used to create stored procedures, functions, and triggers
• Reduces network traffic by executing multiple SQL statements in one block
• Improves performance by processing data in the database instead of client applications

PL/SQL Block Structure

PL/SQL code is written in blocks, which have three main sections:

1. Declaration Section – Used to declare variables and constants.
2. Executable Section – Contains SQL and PL/SQL statements.
3. Exception Handling Section – Used to handle errors.

Example: PL/SQL vs. SQL

SQL Example: Retrieving Employee Data

SELECT EmployeeID, Name, Salary FROM Employees WHERE Department = 'IT';

This simple SQL query retrieves employees from the IT department.

PL/SQL Example: Retrieving Employee Data and Displaying It

DECLARE  
    v_name Employees.Name%TYPE;  
    v_salary Employees.Salary%TYPE;  
BEGIN  
    SELECT Name, Salary INTO v_name, v_salary FROM Employees WHERE EmployeeID = 101;  
    DBMS_OUTPUT.PUT_LINE('Employee Name: ' || v_name || ' Salary: ' || v_salary);  
END;

• This PL/SQL block declares variables (v_name, v_salary), fetches employee data, and prints the result using DBMS_OUTPUT.PUT_LINE.
• Unlike SQL, PL/SQL allows procedural logic (e.g., loops, conditions).

Key Differences Between SQL and PL/SQL

Feature	SQL (Structured Query Language)	PL/SQL (Procedural Language/SQL)
Type	Declarative Language (what to do)	Procedural Language (how to do it)
Execution	Executes single statement at a time	Executes multiple statements as a block
Use Case	Querying and manipulating data	Writing procedures, functions, and business logic
Performance	More network overhead (each query sent separately)	Less network overhead (multiple SQL statements in a single execution)
Error Handling	Minimal error handling	Advanced error handling using EXCEPTION
Supports Loops & Conditions?	No	Yes
Can create Stored Procedures?	No	Yes
Example Usage	SELECT, INSERT, UPDATE, DELETE	Stored procedures, functions, triggers

When to Use SQL vs. PL/SQL?

Use SQL When:

• You need to retrieve, update, delete, or insert data.
• Your operations involve single queries with no business logic.
• You are working with simple data transactions.

Use PL/SQL When:

• You need to perform complex logic using loops, conditions, and variables.
• You want to execute multiple SQL queries together in a single block.
• You need error handling (EXCEPTION).
• You are creating stored procedures, triggers, or functions.

Conclusion

Both SQL and PL/SQL are essential in Oracle Database but serve different purposes. SQL is great for querying and manipulating data, while PL/SQL provides procedural features to handle complex operations efficiently.

If you are starting with Oracle, begin with SQL for data manipulation and later learn PL/SQL to automate and optimize database operations.

Let us know in the comments which one you use the most! 🚀