What is the difference between SQL and PL/SQL?
Both SQL and PL/SQL are languages used to access data within Oracle databases.
SQL is a limited language that allows you to directly interact with the database. You can write queries (SELECT), manipulate objects (DDL) and data (DML) with SQL. However, SQL doesn't include all the things that normal programming languages have, such as loops and IF...THEN...ELSE statements.
PL/SQL is a normal programming language that includes all the features of most other programming languages. But, it has one thing that other programming languages don't have: the ability to easily integrate with SQL.