PL/SQL - Basics

Every PL/SQL program is made of PL/SQL code blocks. There are three types of PL/SQL code blocks:
1) anonymous - they are created in dynamic way and executed only once;
2) named:
- with etiquette - anonymous code blocks with an etiquette which allows to use variables declare inside of this code block;
- subprograms - function, procedures - stored in DB under some name and invoked many times;
- triggers - connected with DB events like invoking DML function (INSERT, UPDATE, DELETE) or DDL function (e.g CREATE, DROP)