SQL, that is abbreviated from Structured Query Languages, is a data oriented language for selecting and operating sets of data. SQL is commonly used by relational database technologies such as Oracle, Microsoft Access, Sybase etc. The term, PL/SQL is a procedural extension of SQL. It is the Oracle native programming language that provides an edge to design database-centric application. Both SQL and PL/SQL languages are designed with a common purpose, to access data within Oracle databases, but PL/SQL is designed to address the limitation of SQL because it cannot be used to manipulate procedural programming with conditional, iterative and sequential statements. To work with PL/SQL, the users normally interact with an application that uses SQL to access a relational database on the back-end.
SQL is widely popular as data oriented language for selecting and executing the sets of data. It is differentiated from the PL/SQL in relation to its capability to create applications that may be the source of data for your screens, web pages and reports while PL/SQL, known as a procedural language, might be used to create format and display those screens, web page and reports that are designed with the help of SQL. It also acts as an application language like Java or PHP can.
The commands and instructions used in SQL aren’t actually a part of the SQL standard but are supported by the tools of SQL and are usually executed to assist format output like BREAK, BTITLE, COLUMN, PRINT or they are meant to create or store data/scripts. It also supports the commands that directly interact with the database to perform the SHUTDOWN, CONNECT or COPY actions. PL/SQL is also known as fourth-generation programming language because of its ability to support the data encapsulation, overloading, collection types, exceptions, and information hiding functions. PL/SQL also offers rapid prototyping and use variables and their declarations, conditional controls like IF and CASE used in other programming languages like C, C++, Java, etc. It also uses looping structures such as LOOP, FOR LOOP and WHILE LOOP.
Another advantage of using PL/SQL is its fast execution speed because it passes a block of statements to be executed to the server, whereas in SQL, only one statement is transferred to the server at a time which is a time consuming process.