Oracle7 Server Application Developer's Guide

Trusted Oracle MLSLABEL Datatype

Trusted Oracle provides one new datatype: the MLSLABEL datatype. You can declare columns of the MLSLABEL datatype in standard Oracle, as well as Trusted Oracle, for compatibility with Trusted Oracle applications. In Oracle7, these columns contain nulls.

The MLSLABEL datatype is used to store the binary format of an operating system label. The maximum width of a column declared as MLSLABEL is 255 bytes.

Any labels that are valid on your operating system can be inserted into an MLSLABEL column. When you insert a label into an MLSLABEL column, Trusted Oracle implicitly converts the data into the binary format of the label.

The ALL_LABELS Data Dictionary View

The ALL_LABELS data dictionary view lists all of the labels ever stored in the database, including the values of DBHIGH and DBLOW. Any label ever stored in an MLSLABEL column (including the ROWLABEL column) is automatically added to this view.

Note that this view does not necessarily contain all labels that are valid in the database, since any valid operating system label, in any valid format, is a valid label within Trusted Oracle. Also note that this view may contain labels that are invalid within the database (if those labels were once used in the database, but are no longer valid).

Adding New Labels

If a label is not already in the ALL_LABELS view, and it is a valid operating system label, it is automatically added to the data dictionary as a valid label when you specify it in an INSERT or UPDATE statement.

For example, if TRULY_SENSITIVE:ALPHA, SENSITIVE, and UNCLASSIFIED are the only labels in the ALL_LABELS view, you can enter SENSITIVE:ALPHA into a column declared as MLSLABEL as long as SENSITIVE:ALPHA is a valid label in your operating system. Once inserted, this label automatically becomes a valid label in Trusted Oracle and is displayed in the ALL_LABELS view.