Large Object (LOB) Columns

LOB columns are columns that contain large amounts of data either in Binary Format (BLOBs) or Character Format (CLOBs). Tables with LOB data can be processed like other data types, and LOB data can be edited and browsed like other data.

LOB columns are displayed in Native or Non-Native mode.

Note: Click the Options button options button in the edit window toolbar and select Table Specifications, Columns, from the Options menu to switch between Native and Non-Native mode.

For columns processed in Non-Native mode, LOB data displays as normal table data, unless the size of the LOB exceeds the Maximum Non-Native LOB Length limitation, set in Personal Options. (Refer to the Common Elements Manual .) If the size exceeds the maximum, the LOB appears truncated, and the grid cell is protected and cross-hatched.

truncated lob data display, described above

For columns processed in Native LOB mode, icons are displayed.

data displayed in native lob mode, described below

The following options are available for LOB columns processed in Native LOB mode:

  • Click the icon to edit the LOB data using the application associated with the LOB. When editing LOB data, you cannot edit other data in the Table Editor. If an application association has not been established for the LOB data, you are prompted to create one.
Note: You cannot undo changes to LOB data.
  • Click the icon to browse a CLOB in character mode.
  • Click the icon to browse the LOB in hex mode.

Display Attributes

You can get additional information about a LOB, by clicking the Options button and selecting Display Attributes from the menu.

lob data display with additional attributes, described below

The LOB data type (BLOB) or (CLOB) is displayed. Additionally, if the DBMS is UDB, the maximum data length is also displayed.

LOB Column Associations

To create LOB column associations, click the Options button options button in the edit window toolbar and select Table Specifications, Columns to display the Columns tab of the Table Specifications dialog.

table specifications columns tab, described below

Use the Association column of the Columns tab to associate a LOB-type column with the application required to view or edit the LOB data (MS Word, NotePad, Paint, etc.), in one of two ways:

  • Enter a file name extension for the type of LOB (for example, type the extension .doc to associate a LOB Word document with Microsoft Word).

    OR

  • Use the drop-down list to select a column name to reference. The first three characters of data in the corresponding row of the referenced column are used as the file name extension for the associated LOB column.
Note: When you attempt to edit LOB data for which an application association has not been established, you are prompted to create one.

When you attempt to edit LOB data associated with an application that is inaccessible from the workstation, Windows 2000 displays the Open with... dialog to allow you to select an accessible application. (Older versions of Windows may display an error message. You can manually assign an accessible application to use by selecting Options, File Types from the Windows View menu.)