Getting Startedwith pureQuery

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Getting Started with pureQuery
10.3.3 In practice: Execute a simple SELECT statement that uses cursor
attributes -- Complete the “Company Employees” screen
The Company Employees screen displays all of the employees in the company in pages of
10 employees each. It allows the user to request additional information about any
particular employee on the screen. The displayAllEmployees (Data data) method
creates this screen. Add the pureQuery code to it to get the employee information from the
database.
10.3.3.1 Use pureQuery to create an Iterator object that
contains the information about the employees
In order to get information about all the employees in the company, we need to execute a
query against the database. We will use the query shown in Listing 10.5, which will select
all the employees and sort them by their names.
SELECT * FROM EMPLOYEE ORDER BY LASTNAME, FIRSTNME, MIDINIT
Listing 10.5 - An SQL query for selecting all the employees in the company
Next, we need to determine which Data method to use. Since we need several pieces of
information about each employee, it would be convenient to retrieve each row as an
instance of EmployeeBean. We therefore need to use a queryXXX method that has a
Class returnClass parameter. We will be selecting all the employees in the
database, but we would prefer not to have to store all of the company's employees in the
application’s memory at once, since that could be quite a lot of memory. As a result, an
Iterator is the most logical object to use to for returning the rows. Therefore, we will
use a queryIterator method that has a Class returnClass parameter.
While users are viewing the list of employees, they can request to view additional
information about an employee and then return to the list. Therefore, we need to set the
cursor holdability to “hold cursors over commit.” As a result, we use a queryIterator
method that has parameters for cursor attributes.
The code to execute our SQL query against the database and create the Iterator is simple.
All we have to do is invoke the queryIterator method, specifying the SQL statement
and EmployeeBean.class. This returns an Iterator object, where
each item is an instance of EmployeeBean. Modify the application to contain this code.
Remember to look for a comment that says TODO: Add pureQuery code here. so that
you will know where you need to add the new code. Listing 10.6 shows the updated code.
// Search the database for all of the employees in the company
// and create an Iterator object to retrieve them.
// Use "hold cursors over commit" so that if the user goes to another
// screen and comes back, we can continue displaying employees.
employees = data.queryIterator (ResultSet.TYPE_FORWARD_ONLY,
ResultSet.CONCUR_READ_ONLY, ResultSet.HOLD_CURSORS_OVER_COMMIT,