Difference between SQL and PL/SQL – A Comparison Guide

Updated on February 24, 2025

Article Outline

What is SQL?What is PL/SQL?Key Difference Between SQL and PL/SQL Applications of SQL and PL/SQL Conclusion FAQs

Data is the key to a company’s growth in every domain, whether artificial intelligence, data science, or machine learning. SQL (Structured Query Language) and PL/SQL (Procedural Language/SQL) play crucial roles in data management. However, though both are meant for database interaction, they differ significantly in purpose, structure, and usage. Regarding handling errors, communicating with databases, and carrying out operations, PLSQL and SQL differ in their respective functions.

This comprehensive guide will discuss the key difference between SQL and PL/SQL, including the features, advantages, disadvantages, and real-world applications. By the end of it, you will have a good understanding of both languages and their appropriate roles within Database Management Systems (DBMS).

Before discussing the key difference between SQL and PL/SQL, we must understand the objectives and background of SQL and PL/SQL since both are essential components of Oracle Database and other databases. SQL stands for Structured Query Language and is the standard language for querying and manipulating data within a relational database. PL/SQL, on the other hand, is an acronym for Procedural Language/Structured Query Language. It is a procedural extension to SQL designed to seamlessly integrate into Oracle’s SQL query and data manipulation facilities.

What is SQL?

SQL is a programming language that doesn’t follow a specific procedure, and it’s used to work with relational databases. IBM developed it in the 1970s, and nearly all relational database systems currently support it. It is highly efficient for working with structured data, making it the go-to language for database interaction. Accessing, managing, and obtaining data from any database is simple when SQL is used. Data manipulation and querying are the main purposes of SQL. It makes data handling easier by enabling users to add, edit, remove, and retrieve data within databases.

SQL provides a higher level of abstraction than procedural languages and is far more portable and upgradeable. SQL can also create and alter the tables, indexes, and database constraints that comprise a database’s schema (structure).

Syntax:

SELECT column1, column2

FROM table_name

WHERE condition;

Example:

SELECT emp_id, f_name, l_name

FROM emp

WHERE dept_id = 30;

In this example, we are retrieving the employee details from the “emp” table where the department ID is 30.

Types of SQL Statements

SQL is divided into several categories depending on its purpose:

1. Data Query Language (DQL): A DQL statement is used to query data from the database.

Example: SELECT statement.

2. Data Manipulation Language (DML): A DML statement manipulates existing table data.

Example: INSERT, UPDATE, DELETE.

3. Data Definition Language (DDL): A DDL statement defines or modifies the structure of database objects like tables, views, etc.

Example: CREATE, ALTER, DROP.

4. Data Control Language (DCL): A DCL statement controls access to data within the database.

Example: GRANT, REVOKE.

5. Transaction Control Language (TCL): A TCL statement is used to manage transactions in the database.

Example: COMMIT, ROLLBACK.

Features of SQL

Below are some key features of SQL:

Standardised: SQL is standardised by ANSI and is a widely used database language.
Declarative language: SQL is a declarative language, which means that instead of explaining how to accomplish a task, you can declare what you want to accomplish (i.e., query data).
Portability: SQL queries can be executed on various database systems with few changes, allowing for smooth cross-platform data administration.
Data control: Using Data Control Language (DCL) statements, SQL can also regulate data access.
Security: SQL offers strong security and administration features, including transaction management and user access control.
Data manipulation: SQL allows querying and manipulating data.
Data definition: SQL can use Data Definition Language (DDL) statements to describe and alter the data structure.

Advantages of SQL

Simplicity and Ease of Use: SQL’s beauty is its subtlety, and it is easy for newcomers to master. After basic training, retrieving information from the database using queries without programming knowledge is possible.
Standardised Language: Because it is an American National Standard Institute format, it is a formulated structure that is the same in every database system with such codes as Mysql, PostgreSQL, and Sql server.
Declarative Nature: In SQL, the user can state what they want to be retrieved but not say how to proceed. This greatly speeds up the writing of queries.
Portability: The SQL language requires only a few changes to run on various databases.
Efficient Data Handling: Including indexing in SQL improves data access speed as the size of data increases; therefore, efficient database operations are recommended.
Powerful Data Manipulation: SQL simplifies adding, modifying, or deleting data from a data-based page.

Disadvantages of SQL

1. Lack of Procedural Logic: The absence of procedural language loops, conditional statements, and other such constructs limits the extent to which SQL can be used for logic in programming.

2. Partial Control: SQL programmers do not completely control the database due to the underlying business rules.

3. Operating Cost: Some programmers find it challenging to access some SQL versions due to their high operating costs.

4. Limited Error Handling: Real situations, on the other hand, showed many limitations regarding how queries were programmed, particularly SQL, regarding errors.

5. Scalability Issues: SQL is unsuitable for managing complex business logic. Such attempts lead to large, tedious, and even unmanageable queries.

6. Overhead for Complicated Operations: When more than two queries are required for an operation, it entails many round trips to the database, making SQL costly.

7. Less Control Over Execution: SQL has some limitations. The execution flow is not controlled at a patch level, which makes implementing very elaborate business logic templates difficult.

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What is PL/SQL?

Procedural Language for SQL, or PL/SQL, is an addition to SQL that Oracle Corporation created. Procedural languages like PL/SQL are made especially to support SQL statements in their syntax. It makes it possible to perform more sophisticated and important operations on the Oracle database by using the declarative qualities of SQL with the procedural characteristics present in programming languages. It allows developers to write complex programs using procedural programming features such as loops, conditions, and variables, making it a more powerful tool for managing databases. It also processes data at a very high speed. The primary reason for the popularity of the PL/SQL language is its ability to manage significant errors.

In the Oracle database context, PL/SQL is mostly used to write and run procedures, functions, triggers, and packages. The procedural language is incredibly strong and extends procedural constructs to SQL statements. The Oracle Database server compiles and stores PL/SQL program units inside the database. SQL and PL/SQL also execute within the same server process at run-time for maximum efficiency. PL/SQL provides the best stability, security, and mobility by inheriting all its features from the Oracle Database.

A PL/SQL block has only four parts: declare, begin, exclude, and end.

Syntax:

DECLARE

variable_name data_type;

BEGIN

-- SQL statements

-- Control structures

-- Exception handling

END;

Example:

DECLARE

CURSOR emp_cursor IS

SELECT emp_id, f_name

FROM emp

WHERE dept_id = 30;

BEGIN

FOR emp IN emp_cursor LOOP

DBMS_OUTPUT.PUT_LINE('Processing employee: ' || emp.f_name);

END LOOP;

EXCEPTION

WHEN NO_DATA_FOUND THEN

DBMS_OUTPUT.PUT_LINE('No employees found.');

WHEN OTHERS THEN

DBMS_OUTPUT.PUT_LINE('An error occurred: ' || SQLERRM);

END;

In this example, we are processing all 30 employees in the department and printing their names.

Types of PL/SQL

The PLSQL allows the creation of four types of objects.

Procedures: These modules execute a defined task and can be called by other procedures , function triggers, or in isolation.

Functions: Just like procedures, functions perform a specific task and return a value.

Triggers: These are special stored procedures automatically executed when a specific event occurs in the database.

Package: PL/SQL packages function as containers which hold various elements including built-in procedures and functions together with variables and constants and exception objects and points to external data. Packages enable users to organize PL/SQL types and objects that share logical relationships.

Features of PL/SQL

Below are some key features of PL/SQL:

Procedural: As PL/SQL is procedural, it allows you to specify the logic behind how operations should be carried out, unlike declarative SQL.
Block of Code: PL/SQL programs comprise declarative, executable, and exception-handling code blocks.
Efficiency: It also allows SQL statements to be executed in batches, which lowers network traffic and boosts performance.
Integration with SQL: PL/SQL and SQL are completely integrated, enabling programmers to run SQL statements inside PL/SQL blocks.
Portability: PL/SQL programs can be run on any platform or operating system and are compatible with Oracle databases.
Functions and Procedures: User-defined functions and procedures for reusable code are supported by PL/SQL.
Control structures: Loops, conditions, and exceptions are examples of procedural control structures that PL/SQL can handle.
Error Handling: Strong error-handling methods with exceptions are provided by PL/SQL.

Advantages of PL/SQL

Use of Procedure Programming Logic: The constructs in PL/SQL can include procedure programming features such as loops, conditionals, and functions, thereby allowing for complex programming logic.
Error Management System: The PL/SQL Error Management System is relational, capturing exceptions and solving errors.
Improved Performance for Complex Operations: PL/SQL combines numerous SQL statements into a single unit to minimise the network load, thus improving the performance of such operations.
Modularity: The procedural-oriented language PL/SQL allows for the code of reusable parts such as procedures, functions, and packages, thereby enhancing the structuring and maintenance of the code.
Business Logic Control: In PL/SQL, the developer can invoke a commit or rollback anywhere in the logic without errors.
Scalability: Scalability is improved by its stored subprograms, which centralise application processing on the database server.

Disadvantages of PL/SQL

Learning Curve: PL/SQL is more difficult than SQL, as it has procedures requiring learning time.
Oracle-Specific: Since PL/SQL is associated with Oracle systems, this could disadvantage projects requiring multiple database systems.
Limited I/O features: I/O operations in PL/SQL which involve reading or writing files and reading or writing to user interfaces can hardly be considered enough
Overhead for Simple Tasks: PL/SQL, however, is often inappropriate, especially for performing simple tasks and queries such as creating functional or data manipulation statements where straight SQL would have sufficed.
Performance Considerations: PL/SQL has an added advantage in that it seeks to reduce the effect of multiple SQL SQL executions against a database when performing a database operation using PL/SQL. Poorly architected PL/SQL codes can lead to SQL bottlenecks.
Complex syntax: Sometimes, programmers have trouble applying PL/SQL because of its complexity and irregular structure.
Development Environment Dependency: PL/SQL is seldom productive when developing without proper and applying Oracle development tools.

Key Difference Between SQL and PL/SQL

The key difference between SQL and PL/SQL are as follows:

Criteria	SQL	PL/SQL
Full Form	SQL stands for Structured Query Language.	PL/SQL stands for Procedural Language/Structured Query Language.
Nature	SQL has declarative syntax.	PL/SQL has declarative syntax.
Syntax	It has a simple syntax and focuses on data manipulation.	It has a complex syntax and supports procedural constructs.
Operations	SQL executes the query and performs a single operation.	PL/SQL block performs a group of operations as a single block.
Error Handling	Limited error handling capabilities.	Advanced error handling through exceptions.
Control Structures	No control structures (loops, conditionals).	Supports control structures (loops, conditions).
Performance	Optimised for data retrieval and manipulation.	Bundles multiple SQL operations, reducing round-trips.
Modularity	SQL is not modular.	PL/SQL supports modular programming, i.e., using procedures and functions.
Integration	SQL can be used independently, i.e., without PL/SQL.	This fully integrates with SQL and supports executing SQL within PL/SQL blocks.
Security	Basic security is achieved through roles and permissions, password settings, etc.	It provides enhanced security through definer and invoker rights.
Environment	It can be executed in any SQL environment.	It requires an Oracle database environment.
Use Cases	Data querying, reporting, CRUD operations.	Complex business logic, triggers, and stored procedures.
Return Types	SQL does not have any return type or values.	PL/SQL can return values from functions.
Learning Type	SQL is very easy to learn.	PL/SQL requires prerequisites as SQL and has a steeper learning curve.
Deployment	SQL statements are deployed in scripts or applications.	PL/SQL programs are deployed in the database as stored procedures.
Processing Speed	For large amounts of data, SQL does not provide fast processing times.	PL/SQL provides high processing speed for large amounts of data.

Applications of SQL and PL/SQL

Here are the different SQL and PL/SQL applications, which are used to manage data in database management systems and provide various features, including security, integrity, efficiency, etc.

Applications of SQL

Data Retrieval: SQL is used to retrieve information from databases for leadership reports and declarations by using SELECT statements in the data tables.
Data Manipulation: Adding records data in the database or changing some details and removing some data from the database using the commands INSERT, UPDATE, and DELETE.
Database Management: Building relations including foreign keys (like primary and foreign keys) and creating new records for database objects such as tables, indexes, and views, using the CREATE, ALTER, and DROP commands.
Data Science and Machine Learning: Adopting the concepts of SQL is an added advantage for data scientists and machine Learning engineers. This is mostly because they work with big amounts of data.
Data Analysis: This includes performing complex queries,, such as, joins, scalars, and group-by subqueries,, to helpdraw insights from the data.
Web Development: In web development, web databases are queried, and SQL is one method used to do so. This is very important because it helps create dynamic web applications that use data, store data, retrieve it, and process it, thereby presenting a better way for end users to interact with applications.
Reporting: Data in preparation for reports or dashboards is accessed or retrieved, typically combined with business intelligence.
Business Intelligence (BI) is a process that focuses on extracting valuable insights from available data using SQL. Users can use SQL for decision support, analytical reporting, and market analysis.

Applications of PL/SQL

Stored Procedures and Functions: PL/SQL helps develop procedures and functions that contain business logic in a reusable manner for improving structure and maintenance.
Batch Processing: Normal reporting, which requires several SQL operators,, is carried out by carrying out all the commands in one single PL/SQL block.
Customer Relationship Management (CRM): PL/SQL is also used to implement business logic specifically in CRM systems and integrate applications with databases.
Triggers: Creating procedures for database tables automating a particular activity triggered by an event and could involve changing some data.
Complex Business Logic: Permitting or carrying out complicated business rules that need many activities and conditions to be completed by the database.
Enterprise Resource Planning (ERP): Most provisions of PL/SQL are utilised in application development, integration, and customization of business solutions in Oracle E-Business Suite ERP systems, e.g. Sigma.
Data Validation: Ensuring the validation and integrity of data before inserting or updating any record is executed using PL SQL.
Business Intelligence: Many data processed using PL SQL is used to generate reports and meet various other analytical needs, especially within BI.

Conclusion

The two languages, SQL and PL/SQL, serve different purposes but are used together to manage a database. SQL is the language best suited for carrying out queries upon relations or modifying and managing relations. PL/SQL, on the other hand, enhances the power of SQL with the power of procedural programming to meet the needs of more sophisticated business logic and automation in the database.

Understanding the key difference between SQL and PL/SQL, their features, and their appropriate use cases is crucial for any database administrator or developer. While SQL is great at organising and accessing data, PL/SQL performs better in situations requiring more control over procedural logic, error handling, and execution flow. Both languages are essential for the smooth administration and operation of contemporary databases, especially in settings where Oracle databases are used. To deepen your SQL knowledge, consider enrolling in the Certification Program in Data Analytics offered by Hero Vired in collaboration with Microsoft.

FAQs

Is PL/SQL only available for Oracle databases?

Yes, PL/SQL is an in-house language of the Oracle Corporation intended to use exclusively in Oracle Databases. It allows the execution of complex database queries with exception handling.

Which is easier to learn, SQL or PL/SQL?

Because SQL is declarative, it is easier to learn than PL/SQL, which has a higher learning curve because of its procedural capabilities.

Can we SQL in PL/SQL?

Yes, PL/SQL and SQL are fully integrated, enabling the execution of SQL queries inside PL/SQL blocks. When the users want more control over their query, they prefer using PL/SQL as it provides the best exception handling, running groups of queries, and much more.

What is the main difference between SQL and PL SQL?

The main difference between the two is that SQL is a query language while PL/SQL is a procedural language. SQL allows users to improve themselves as much as possible by giving them control and limits over the data. PL/SQL allows developers to write programs with control structures, manage exceptions, and create reusable modules like functions, procedures, and triggers.

What is the difference between PL SQL and T-SQL?

PL/SQL offers more procedural capabilities than SQL. Also, T-SQL is less generic than normal SQL as it is centred around a particular database management system. PL/SQL is specific to Oracle databases, but T-SQL attaches itself to Microsoft SQL Server. This, however, does not mean that they cannot be used for similar reasons. For instance, PL/SQL or T-SQL could implement complex business logic, automate database operations, etc.

Updated on February 24, 2025

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