Here we discuss examples for different cases of usage for stored procedures and stored functions. Please refer to the note on ‘Stored Procedures and Stored Functions in MySQL’ for more theory, details and explanations.

A stored routine allow users to define a set of statements that they can later call together. Stored procedures and stored functions are the two types of stored routines in MySQL. A stored procedure takes in zero or more input parameters and runs specified SQL statements. A stored function takes in zero or more parameters, runs specified SQL, and returns exactly one scalar value.

A trigger is a set of commands invoked automatically when an SQL statement changes data on the associated table. Other stored SQL types in MySQL are events, stored procedures, and stored functions.

The WHERE clause lets you add further conditions on your query. We will see the use of WHERE clauses along with other clauses that will help us refine our queries in this section.

Similar to scope and lifetime of variables in Java as you have seen in blocks-and-methods-in-java, parameters and attributes in a Java EE web application also have scope and lifetime in the context of the web application. The scope of a parameter/attribute denotes the availability of that parameter/attribute for use. A web application serves multiple requests from clients when it is up and running. These requests can be from same client or different clients.