TurboIMAGE/XL Database Management System Reference Manual (30391-90012)

52 Chapter2
Database Structure and Protection
Protecting the Database
The combinations of the data set and data item user class lists result in one of the
following five types of access:
• Write access
• Update access
• Read access
• No access
• Creator-only access
Write Access A user class that has write access can add entries to or delete from the data
set. Write access means that update and read access are also granted, and is sometimes
referred to as full data access. To grant write access to a user class for a data set, include
the user class number in the write list of the data set. The specified user class then needs
to open the database using mode 1, 3, or 4 to take advantage of write access. The user class
is ignored if it appears in the user class lists of data items that belong to the data set
because write access to a user class at the data set level supersedes that at the item level.
NOTE Database access modes 2, 5, 6, 7, and 8 do not allow write access. Programs
that open the database in these modes must pass data set and data item level
security. For additional information, refer to chapter 4 and to "Database
Access Modes and Data Set Write Lists" later in this chapter.
Update Access A user class that has update access can change the values of a particular
data item in an existing data entry. However, the user class cannot add or delete entries
from the data set. Update access means that read access is also granted. To grant update
access to a user class for a data item, include the user class in the read list of the data set
and in the write list of the data item. The specified user class then needs to open the
database in mode 1, 2, 3, or 4 to take advantage of this type of access. The user class can
have update, read, or no access to other data items in the data set depending on the user
class lists of the other data items.
NOTE TurboIMAGE/XL provides an option called critical item update (CIUPDATE)
which lets you update the values of detail data set search and sort items if the
database access mode is 1, 3, or 4 and if permitted for the current process. You
can restrict update of these data items by assigning read-only access at the
set level and controlling write or update access at the item level. See chapter
4 for more information on CIUPDATE.
Read Access A user class that has read access can only view the values of a particular
data item. To grant read access to a user class for a data item, include the user class in the
read class list of the data set and in the read class list of the data item. This user class can
have update, read, or no access to other data items in the data set depending on the user
class lists of the other items.
No Access A user class that has no access cannot read data item values. No access to a
user class can be defined for an entire data set or for specific data items in a data set.