SQL (Structured Query Language) and PL/SQL (Procedural Language/Structured Query Language) are both used in the context of relational databases, but they serve different purposes and have distinct characteristics. Here are five main differences between SQL and PL/SQL:
Purpose:
SQL: SQL is a domain-specific language used for managing and manipulating relational databases. It is primarily focused on querying databases to retrieve, insert, update, and delete data. SQL is used for tasks such as creating and modifying database structures (tables, indexes, etc.) and managing the data within those structures.
PL/SQL: PL/SQL, on the other hand, is a procedural language extension for SQL. It is designed for the development of stored procedures, functions, triggers, and other procedural constructs. PL/SQL allows for the creation of more complex and procedural logic to be executed within the database.
Type of Language:
SQL: SQL is a declarative language. Users specify what data they want and how they want it, but they do not necessarily specify how to retrieve it. SQL statements describe the result set and let the database management system determine the most efficient way to obtain it.
PL/SQL: PL/SQL is a procedural language. It allows developers to write procedural code that can include conditional statements, loops, exception handling, and other programming constructs. PL/SQL programs are typically executed as a series of statements in a predefined order.
Execution Context:
SQL: SQL statements are typically executed on the database server. They are used to interact with the data stored in the database and are submitted to the database server for processing.
PL/SQL: PL/SQL is executed within the Oracle Database environment. It is processed by the Oracle Database server, and it allows for the creation of stored procedures, functions, and triggers that can be executed on the server side.
Usage:
SQL: SQL is used for managing and querying databases. It is employed in tasks such as creating and altering database structures, retrieving data, and performing operations on the data.
PL/SQL: PL/SQL is used for developing procedural code that can be executed within the Oracle Database. It is commonly used for creating stored procedures, functions, and triggers that encapsulate business logic within the database.
Integration:
SQL: SQL can be embedded in other programming languages and applications to interact with databases. It is often used in conjunction with programming languages like Java, Python, or C# to build database-driven applications.
PL/SQL: PL/SQL is specific to Oracle Database systems. It is tightly integrated with the Oracle Database and is used for creating database-specific procedural logic. PL/SQL is not as portable as SQL, which can be used with different database systems.
In summary, SQL is a language for querying and managing databases, while PL/SQL is an extension of SQL designed for procedural programming within the Oracle Database environment. SQL is declarative, focusing on what data to retrieve, while PL/SQL is procedural, allowing developers to define how specific tasks are carried out within the database.