more on creating database forms using appbuilder

Copyright Oracle Corporation, 1998. All rights reserved.

55

More on Creating Database Forms Using AppBuilder

More on Creating Database Forms Using AppBuilder

Copyright Oracle Corporation, 1998. All rights reserved.5-5-22

ObjectivesObjectives

After completing this lesson, you should be able to do the following:

• Create master-detail forms

• Use JBCL components programmatically in Java code

• Filter and sort data records

• Use data modules, and perform parameterized queries

After completing this lesson, you should be able to do the following:

• Create master-detail forms

• Use JBCL components programmatically in Java code

• Filter and sort data records

• Use data modules, and perform parameterized queries


Master-Detail RelationshipsMaster-Detail Relationships

LOC

NEW YORK

DALLAS

CHICAGO

BOSTON

DEPTNO

10

20

30

40

DNAME

ACCOUNTING

RESEARCH

SALES

OPERATIONS

Master table, Master table, DEPTDEPT

EMPNO

7839

7782

7934

7566

7902

ENAME

KING

CLARK

MILLER

JONES

FORD

Details table, Details table, EMPEMP

DEPTNO

10

10

10

20

20


Master-Detail Form at Run TimeMaster-Detail Form at Run Time

This is how the Master-Detail form will appear at run time

Master section

Detail section

This is how the Master-Detail form will appear at run time

Master section

Detail section


Two or more QueryDataSets are required in a master-detail formTwo or more QueryDataSets are required in a master-detail form

Specifying QueryDataSet Properties

Specifying QueryDataSet Properties

Detail query Detail query Master query Master query


Establishing the Master-Detail Relationship

Establishing the Master-Detail Relationship

Specify masterLink property in detail QueryDataSet

Specify masterLink property in detail QueryDataSet


Connecting the Master Query to the Detail Query

Connecting the Master Query to the Detail Query

This column in themaster query … This column in themaster query …

… is linked to thiscolumn in the detail query

… is linked to thiscolumn in the detail query


Data-aware controls can now be added to display the fields

Fields attached to master query

Fields attached to detail query

Data-aware controls can now be added to display the fields

Fields attached to master query

Fields attached to detail query

Using the Master and Detail QueryDataSets

Using the Master and Detail QueryDataSets


Delayed FetchingDelayed Fetching

• Delayed fetching can improve performance

• Data in the “details” data set is fetched only when needed

• Select “Delay fetch…” check box in masterLink editor

• A WHERE clause is required in the SQL string of the detail QueryDataSet

• Delayed fetching can improve performance

• Data in the “details” data set is fetched only when needed

• Select “Delay fetch…” check box in masterLink editor

• A WHERE clause is required in the SQL string of the detail QueryDataSet


Calculated ColumnsCalculated Columns

• It is also possible to define calculated columns in a QueryDataSet

• It is also possible to define calculated columns in a QueryDataSet

ENAME

KING

CLARK

MILLER

ANNUAL_SAL

29400

60000

15600

SAL

2450

5000

1300


Adding a Calculated Column to a QueryDataSet

Adding a Calculated Column to a QueryDataSet

1. Select <new column> in theQueryDataSet

2. Open Inspector window

3. Set calcType field to calculated

4. Set columnName and dataType

1. Select <new column> in theQueryDataSet

2. Open Inspector window

3. Set calcType field to calculated

4. Set columnName and dataType


Supplying a Value for a Calculated Field

Supplying a Value for a Calculated Field

When a calculated field needs evaluation:

• QueryDataSet component generates a calcFields event

• You must handle this event

When a calculated field needs evaluation:

• QueryDataSet component generates a calcFields event

• You must handle this event


Guided Practice: Providing calcFields Handler MethodGuided Practice: Providing calcFields Handler Method

Explain the following handler method: Explain the following handler method:

import java.math.BigDecimal; // Standard class

…

void queryDetail_calcFields(ReadRow readRow,

DataRow dataRow,

boolean boolean1) … {

BigDecimal sal, ann;

sal = readRow.getBigDecimal("SAL");

ann = sal.multiply(new BigDecimal(12));

dataRow.setBigDecimal("ANNUAL_SAL", ann);

}


Calculated Columns at Run Time

Calculated Columns at Run Time

The GridControl displays the calculated column automatically

Calculated column

The GridControl displays the calculated column automatically

Calculated column


Filtering RowsFiltering Rows

If required, a filter can be defined for a QueryDataSet

Example: Filteremployees earning less than a certainamount

If required, a filter can be defined for a QueryDataSet

Example: Filteremployees earning less than a certainamount


QueryDataSets Generate filterRow Events

QueryDataSets Generate filterRow Events

• A filterRow event is generated before each row is added to the data set

• You provide a handler method, to decide whether to keep or reject the row

• A filterRow event is generated before each row is added to the data set

• You provide a handler method, to decide whether to keep or reject the row


Supplying a Handler Method to Filter Rows

Supplying a Handler Method to Filter Rows

void queryDetail_filterRow(

ReadRow readRow,

RowFilterResponse rowFilterResponse)… {

String txt = txtMinSal.getText();

if (txt.equals(""))

txt = "0.0";

BigDecimal min = new BigDecimal(txt);

BigDecimal sal = readRow.getBigDecimal("SAL");

if (sal.compareTo(min) >= 0)

rowFilterResponse.add();

}


Forcing a Row Filter to Occur Forcing a Row Filter to Occur

void btn_actionPerformed(ActionEvent e) {

try {

queryDetail.refilter();

}

catch(DataSetException dse) {}

}

Call refilter() to force rows to be refiltered

Call refilter() to force rows to be refiltered


Sorting RowsSorting Rows

A data set can be dynamically re-sorted at any time

Example: ChoiceControlcan specify thesort column

A data set can be dynamically re-sorted at any time

Example: ChoiceControlcan specify thesort column


Performing a Sort ProgrammaticallyPerforming a Sort Programmatically

void choiceControl1_itemStateChanged(ItemEvent e){

String[] s = new String[1];

s[0] = choiceControl1.getSelectedItem();

SortDescriptor sd;

sd = new SortDescriptor(s, true, false);

try {

queryDetail.close();

queryDetail.setSort(sd);

queryDetail.open();

} catch (DataSetException dse) {}

}


Practice 5-1 OverviewPractice 5-1 Overview

• Define a master-detail form

• Add a calculated column to a QueryDataSet

• Add a filter to a QueryDataSet

• Add sort capabilities to a QueryDataSet

• Define a master-detail form

• Add a calculated column to a QueryDataSet

• Add a filter to a QueryDataSet

• Add sort capabilities to a QueryDataSet


The Bigger PictureThe Bigger Picture

• The programs we have seen so far comprise a single applet

• The applet contains the Database and QueryDataSet components

• The programs we have seen so far comprise a single applet

• The applet contains the Database and QueryDataSet components

database1

queryDataSet1

queryDataSet2Java appletJava applet


Working with Larger ProgramsWorking with Larger Programs

• Complex programs can have many frames

• Each frame may need its own Database and QueryDataSet components

• Complex programs can have many frames

• Each frame may need its own Database and QueryDataSet components

database1

queryDataSet1

queryDataSet2

Java appletJava applet

database1

queryDataSet1

queryDataSet2

Frame 1Frame 1

database1

queryDataSet1

queryDataSet2

Frame 2Frame 2


The Benefit of Data ModulesThe Benefit of Data Modules

To avoid duplication, data components can be placed in a shared Data ModuleTo avoid duplication, data components can be placed in a shared Data Module

database1

queryDataSet1

queryDataSet2

Data moduleData module

AppletApplet

Frame 1Frame 1

Frame 2Frame 2

queryDataSet3


Creating a Data Modulein AppBuilder

Creating a Data Modulein AppBuilder

• Select File—>New, and double-clickthe Data Moduleicon

• Select File—>New, and double-clickthe Data Moduleicon

• Fill in details for the new data module

• Fill in details for the new data module


Adding Components to a Data Module

Adding Components to a Data Module

Add shared Database and QueryDataSet components to the data moduleAdd shared Database and QueryDataSet components to the data module


Linking an Applet to a Data Module

Linking an Applet to a Data Module

Applets can be linked to a data module, as follows:

• Data module automatically added to Structure Pane

Applets can be linked to a data module, as follows:

• Data module automatically added to Structure Pane

public class MyApplet extends Applet {

MyDataModule dm = MyDataModule.getDataModule();

XYLayout xYLayout1 = new XYLayout(); // Etc

…

};


Designing the Applet User Interface

Designing the Applet User Interface

• Data-aware controls can be added to the

applet, as usual

• The QueryDataSet is now located in the data module

• Data-aware controls can be added to the

applet, as usual

• The QueryDataSet is now located in the data module


Adding a Frame to Display Orders Information

Adding a Frame to Display Orders Information

• Select File—>New, and double-clickthe Frame icon

• Select File—>New, and double-clickthe Frame icon

• Fill in details for the new frame

• Fill in details for the new frame


Linking a Frame to a Data Module

Linking a Frame to a Data Module

• Frames are linked to a data module in exactly the same way as for applets:

• Data module automaticallyadded to the Structure Pane

• Frames are linked to a data module in exactly the same way as for applets:

• Data module automaticallyadded to the Structure Pane

public class MyFrame extends DecoratedFrame {

MyDataModule dm = MyDataModule.getDataModule();

XYLayout xYLayout1 = new XYLayout(); // Etc

…

};


Specifying a SQL String to Populate the Frame

Specifying a SQL String to Populate the Frame

• Our frame will display all the orders made by a selected customer

• Define a separate QueryDataSet to perform this query

• Place this query in the data module

• Our frame will display all the orders made by a selected customer

• Define a separate QueryDataSet to perform this query

• Place this query in the data module

select ORDID, ORDERDATE, SHIPDATE, TOTAL

from ORD

where CUSTID = :currCust


Defining Parameterized RowsDefining Parameterized Rows

• The Orders query takes a parameter to specify the current customer

• This parameter must be represented by a ParameterRow object:

• The Orders query takes a parameter to specify the current customer

• This parameter must be represented by a ParameterRow object:

void jbInit() … { // Code in MyDataModule

ParameterRow pr = new ParameterRow();

pr.addColumn("currCust", Variant.BIGDECIMAL);

pr.setBigDecimal("currCust", new BigDecimal(0));

queryOrders.setQuery(

new QueryDescriptor(…, pr, true, false));

}


Executing the Orders QueryExecuting the Orders Query

void btnControl1_actionPerformed(ActionEvent e) {

try {

QueryDataSet qc = dm.getQueryCustomers();

BigDecimal custid = qc.getBigDecimal("CUSTID");

QueryDataSet qo = dm.getQueryOrders();

ReadWriteRow pr = qo.getParameterRow();

pr.setBigDecimal("currCust", custid);

qo.executeQuery();

new MyFrame().show();

} catch(DataSetException dse) {}

}


Putting It All Together Putting It All Together


SummarySummary

• Master-detail forms can be defined, using the masterLink property

• Calculated columns can be added to a data set

• Rows can be filtered and sorted

• In large programs, a data module can be used for shared components

• Parameterized queries can be used to specify query values at run time

• Master-detail forms can be defined, using the masterLink property

• Calculated columns can be added to a data set

• Rows can be filtered and sorted

• In large programs, a data module can be used for shared components

• Parameterized queries can be used to specify query values at run time


Practice 5-2 OverviewPractice 5-2 Overview

• Define a data module

• Attach a panel to the data module, and add the panel to an applet

• Attach a frame window to the data module

• Launch the frame window from the applet

• Define a data module

• Attach a panel to the data module, and add the panel to an applet

• Attach a frame window to the data module

• Launch the frame window from the applet

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