PL/SQL stands for "Procedural Language extensions to the Structured Query Language."
SQL is for both querying and updating relational databases.
PL/SQL is tight integration with SQL.
PL/SQL, the Oracle procedural extension of SQL, is a portable, high-performance transaction-processing language.
With PL/SQL, you can use all SQL data manipulation, cursor control, and transaction control statements, and all SQL functions, operators, and pseudocolumns.