Getting Startedwith pureQuery

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Getting Started with pureQuery
• Have predefined queries
Use pureQuery inline style if you:
• Like to have your SQL statements inline in your Java code, just like regular JDBC
programming
• Have dynamically generated queries
As a rule of thumb, we recommend using the annotated method stule. Due to its flexibility
and isolation from the business logic, the annotated method style simplifies tasks like
refactoring, because code is in a single place, and code reutilization, by sharing your data
access interfaces between projects.
Keep in mind that you can also mix both programming styles in your application if your
requirements cannot be met by a single style.
14.3 Perform Joins with Table collation
In addition to the basic data access generated by pureQuery tooling for a database table,
sometimes you need to run a more complex query that joins two tables, and return
information from both tables as Java beans.
Table collation in pureQuery lets you reuse the generated beans in these types of queries,
returning multiple beans for each result row.
Consider the SQL statement in Listing 14.1, which shows a query that joins data from the
tables PROJECT and DEPARTMENT:
SELECT PROJECT.PROJNO, DEPARTMENT.DEPTNO
FROM PROJECT, DEPARTMENT
WHERE PROJECT.DEPTNO = DEPARTMENT.DEPTNO
Listing 14.1 - Selecting data from the tables PROJECT and DEPARTMENT
By using pureQuery’s table collation feature, you can specify that the result of this query
should be represented in the business layer using the Project and Department pureQuery
beans, which you can easily generate using tooling.
In order to hold these beans in a result set, you need to define a generic class that can
hold the two beans and be used as the pureQuery API method return type:
public class ProjectAndDepartment extends LinkedList
{}
Listing 14.2 - Generic class to hold a pair of beans
You can then use this class as the type for the Iterator or List returned by your data access
API: