Working with databases

Lesson 9: Manipulating data

This lesson will show how to use a business process to manipulate data.

From within the DataFlex Studio select the ‘Create New’ icon from the top toolbar.
Select the ‘Other’ tab.
Select ‘Business Process.’ Select OK.
Enter “ReduceRating” as the ‘Object Name.’ Select OK.
Write a find loop to calculate the rating of each recipe…
Use the DDO Explorer on the right to add objects…
Select the ‘Add DDO’ icon from the top of the panel.
Select ‘cRecipeDataDictionary’ form the list. Select ‘Select.’
Write a find loop in ReduceRating.bp…
Procedure OnProcess
Integer iRating
Boolean bErr

Send Find of oRecipe_DD FIRST_RECORD 1
While (Found)
Send Update_Status (“Processing: “ + Field_Current_Value(oRecipe_DD, RefTable(Recipe.Name)))

Get Field_Current_Value of oRecipe_DD (RefTable(Recipe.Rating)) to iRating

Decrement iRating

If (iRating < 0) Begin
Move 0 to iRating
End

Set Field_Changed_Value of oRecipe_DD (RefTable(Recipe.Rating)) to iRating

Get Request_Validate of oRecipe_DD to bErr
If (not(bErr)) Begin
Send Request_Save of oRecipe_DD
End

Send Find of oRecipe_DD NEXT_RECORD 1
Loop
End_Procedure
This business process now needs to be added to the application…
Navigate to source view of ‘Cookbook.src’
Scroll to the bottom to add a Use statement…
Use ReduceRating.bp
Add a menu item to the application’s toolbar…
From the design view of ‘Cookbook.src [Design]’…
Click ‘Help’ on the application’s menu.
Click on the ‘Type Here’ prompt that appears.
Enter “Reduce Rating,” hit ENTER.
Double click the text you just entered to open the source code where it has created a C Codejock menu item (cCJMenuItem).
From within the menu item write code to implement the onExecute event.
Press CTRL+2 to open the ‘Properties’ panel on the right for the specified object (the cursor must be located on the desired object).
Select the ‘Events’ tab.
Double click ‘OnExecute’ to generate the onExecute procedure in the code that will be triggered when the menu item is clicked.
Add details to the code
Send doProcess of oReduceRating
To properly see the results of the procedure…
Open the ‘Table Explorer’ on the left.
Right click ‘Recipe,’ and select ‘View Table’ to the see the recipes and their ratings.
Select the ‘Run’ icon from the top toolbar to launch the application.
Select ‘Reduce Ratings’ from the application’s top menu. A status window will quickly show the process being run.
Return to the ‘Recipe [Table Viewer]’ in the Studio, and select the ‘refresh’ icon to see that the ratings have been reduced.

Working with Databases

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Working with databases

Lesson 9: Manipulating data