Creating an OLE column – PB Docs 2018

• The id column is an integer and serves as the table’s
  key.

• The object column is a blob datatype and contains OLE
  objects associated with several OLE servers.

To create the database table

1. In the Database painter, create a table to hold the blob
   (binary large-object) data.

   The table must have at least two columns: a key column and a
   column with the blob datatype. The actual datatype you choose
   depends on your DBMS. For example, in SQL Anywhere, choose long
   binary as the datatype for the blob column. For information about
   datatypes, see your DBMS documentation.

2. Define the blob columns as allowing NULLs (this allows you
   to store a row that does not contain a blob).

To add a blob column to a new DataWindow object

1. Create a new DataWindow object.

2. Specify the table containing the blob as the data source for
   the DataWindow object.

   Be sure to include the key column in the data source. You
   cannot include the blob column in the data source; if you try, a
   message tells you that its datatype requires the use of an
   embedded SQL statement. You add the blob column later in the
   DataWindow painter workspace. (If you use Quick Select, the blob
   column is not listed in the dialog box.)

3. Select Insert>Control>OLE Database Blob and click
   where you want the blob column in the Design view.

   The Database Binary/Text Large Object dialog box
   displays:

   

To set properties for a blob column

1. (Optional) Enter the client class in the Client Class box.
   The default is DataWindow.

   This value is used in some OLE server applications to build
   the title that displays at the top of the server window.

2. (Optional) Enter the client name in the Client Name box. The
   default is Untitled.

   This value is used in some OLE server applications to build
   the title that displays in the title bar of the server
   window.

3. In the Table box, select the database table that contains
   the blob database column you want to place in the DataWindow
   object.

   The names of the columns in the selected table display in
   the Large Binary/Text Columns list.

4. In the Large Binary/Text Columns box, select the column that
   contains the blob datatype from the list.

5. If necessary, change the default key clause in the Key
   Clause box.

   PowerBuilder uses the key clause to build the WHERE clause
   of the SELECT statement used to retrieve and update the blob
   column in the database. It can be any valid WHERE clause.

6. Use colon variables to specify DataWindow columns. For
   example, if you enter this key clause:

   PowerBuilder

   id = :id

   1

   id = :id

   the WHERE clause will be:

   PowerBuilder

   WHERE id = :id

   1	WHERE id = :id

7. Identify the OLE server application by doing one of the
   following:

   • If you always want to open the same file in the OLE
     server application, enter the name of the file in the File
     Template box.

     For example, to specify a particular Microsoft Word
     document, enter the name of the DOC file. If the file is not
     on the current path, enter the fully qualified name.

     Use the Browse button to find the file

     If you do not know the name of the file you want to
     use, click the Browse button to display a list of available
     files. Select the file you want from the resulting
     window.

   • If you do not want to open the same file each time,
     select an OLE server application from the OLE Class:
     Description drop-down list.

     When the server does not match the OLE blob
     data

     If you specify a server that does not match the OLE
     blob object or if your database contains objects belonging
     to different servers, the OLE mechanism can usually handle
     the situation. It looks for the server specified in the
     object and starts it instead of the server you
     specified.

8. Enter text or an expression that evaluates to a string in
   the Client Name Expression box.

   The server might use this expression in the title of the
   window in the OLE server application. The expression you specify
   can identify the current row in the DataWindow object.

   Use an expression to make sure the name is unique

   To make sure the name is unique, you should use an
   expression. For example, you might enter the following
   expression to identify a document (where id is the integer key
   column):

   PowerBuilder

   "Document " + String(id)

   1	"Document " + String(id)

9. Click OK.

   PowerBuilder closes the dialog box. The blob column is
   represented by a box labeled Blob in the Design view.

10. Save the DataWindow object.

    The following screenshot shows what a completed Definition
    page for a Blob object in a table called ole looks like in the
    Properties view:

    

To preview an OLE column in preview mode

1. Select File>Run/Preview from the menu bar and select the
   DataWindow object.

2. Click the Insert Row button.

   PowerBuilder adds a blank row.

3. In the blank row, enter a value in the key column.

4. Double-click the column that contains the blob
   datatype.

   The OLE server application starts and displays the file you
   specified in the File Template box, or an empty workspace if you
   specified only the OLE server name.

5. Review the file in the OLE server application and make
   changes if you want.

   When you use an OLE column to access an OLE server
   application, the server application adds an item to its File menu
   that allows you to update the data in the server application and
   in the client (the DataWindow object). The text of the menu item
   depends on the OLE server application. In most applications, it is
   Update.

6. Select the menu item in the OLE server that updates the OLE
   client with the modifications.

   In the example, you would select Update from the File menu
   in Microsoft Word. The OLE server application sends the updated
   information to the DataWindow object.

7. Close the file in the server application (typically by
   selecting Close from the File menu).

8. To save the blob data in the database, click the Save
   Changes button in the PainterBar.

   The new row, including the key value and the blob, is stored
   in the database.

   Later, after you retrieve the rows from the database, you
   can view and edit the blob by double-clicking it, which invokes
   the OLE server application and opens the stored document. If you
   make changes and then update the database, all the modified OLE
   columns are stored in the database.