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.

DDL stands for Data Definition Language, and these queries are used to create or manipulate the structure of the database and schemas. Here we will see basic DDL queries that you will use in general. Please feel free to add more through the comments section.

First we will look at some commonly asked questions based on the contents of this page. You can refer to getting-started-with-oracle-xe-and-jdbc-hands-On for setting up oracle xe and database for examples here: create 2 tables employee and emp, with 2 columns empName and id; and insert data with ids ranging from 1 to 5. You might have to use some common sense for some of the examples, like deleting/modifying duplicate data.