Enterprise Application Development with Ext JS and Spring

Introducing the Java Persistence Query Language

Everyone reading this book should be familiar with SQL queries and how they work. Constructing a simple query against the ttt_company table to retrieve all records would look something like:

select * from ttt_company

Restricting the result set to companies starting with G would look like the following code line:

select * from ttt_company where company_name like "G%"

In JPA, we are dealing with entities and relationships between entities. The Java Persistence Query Language (JPQL) is used to formulate queries in a similar way to SQL. The previously mentioned statement will be written in JPQL as follows:

SELECT c FROM Company c

And the statement that follows is written as such:

SELECT c FROM Company c WHERE ...