MDAC 2.5 SDK - ADO

Address Book Command Buttons

See Also

The Address Book application includes the following command buttons:

• A Find button to submit a query to the database.
  
  
• A Clear button to clear the text boxes before starting a new search.
  
  
• An Update Profile button to save changes to an employee record.
  
  
• A Cancel Changes button to discard changes.

Find Button

Clicking the Find button activates the VBScript Find_OnClick Sub procedure, which builds and sends the SQL query. Clicking this button populates the data grid.

Building the SQL Query

The first part of the Find_OnClick Sub procedure builds the SQL query, one phrase at a time, by appending text strings to a global SQL SELECT statement. It begins by setting the variable myQuery to an SQL SELECT statement that requests all rows of data from the data source table. Next, the Sub procedure scans each of the four input boxes on the page.

Because the program uses the word like in building the SQL statements, the queries are substring searches rather than exact matches.

For example, if the Last Name box contained the entry "Berge" and the Title box contained the entry "Program Manager", the SQL statement (value of myQuery) would read:

Select FirstName, LastName, Title, Email, Building, Room, Phone from Employee where lastname like 'Berge%' and title like 'Program Manager%'

If the query was successful, all persons with a last name containing the text "Berge" (such as Berge and Berger), with a title containing the words "Program Manager" (for example, Program Manager, Advanced Technologies) are displayed in the HTML data grid.

Preparing and Sending the Query

The last part of the Find_OnClick Sub procedure consists of two statements. The first statement assigns the SQL property of the RDS.DataControl object equal to the dynamically built SQL query. The second statement causes the RDS.DataControl object (DC1) to query the database, and then display the new results of the query in the grid.

Sub Find_OnClick
   ‘...
   DC1.SQL = myQuery
   DC1.Refresh
End Sub

Update Profile Button

Clicking the Update Profile button activates the VBScript Update_OnClick Sub procedure, which executes the RDS.DataControl object's (DC1) SubmitChanges and Refresh methods.

Sub Update_OnClick
   DC1.SubmitChanges
   DC1.Refresh
End Sub

When DC1.SubmitChanges executes, the Remote Data Service packages all the update information and sends it to the server via HTTP. The update is all-or-nothing; if a part of the update isn't successful, none of the changes is made, and a status message is returned. DC1.Refresh isn't necessary after SubmitChanges with Remote Data Service, but it ensures fresh data.

Cancel Changes Button

Clicking Cancel Changes activates the VBScript Cancel_OnClick Sub procedure, which executes the RDS.DataControl object's (DC1) CancelUpdate method.

Sub Cancel_OnClick
   DC1.CancelUpdate
End Sub

When DC1.CancelUpdate executes, it discards any edits that a user has made to an employee record on the data grid since the last query or update. It restores the original values.

Next   Address Book Navigation Buttons