TurboIMAGE/XL Database Management System Reference Manual MPE/iX V6.5 (30391-90011)

96 Chapter4
Using the Database
Opening the Database
detail data set search and sort items to be updated and which is discussed later in this
chapter, is not available in this mode.
• Modify access modes (1, 3, and 4) allow updates and permit the user to add and delete
entries. For access modes 1, 3, and 4 only, users can update the values of detail data set
search and sort items if the critical item update (CIUPDATE) option settings for the
database and the current process permit them to do so. CIUPDATE is discussed later in
this chapter.
The TurboIMAGE/XL library procedures (also called intrinsics) that can be used with each
type of DBOPEN mode are as follows:
Table 4-2. summarizes the type of database access granted in each access mode, provided
the MPE/iX security provisions and your password permit it. Access modes 3 and 7 provide
exclusive access to the database; all other modes allow shared access.
Concurrent Database Access Modes
A database can only be shared in certain well-defined environments. The access mode
specified when a process opens a database must be acceptable for the environment
established by others who are already using the database.
Table 4-1. Library Procedures DBOPEN Modes
DBOPEN Mode Library Procedures Available
Read DBFIND and DBGET
Update DBFIND, DBGET, and DBUPDATE
Modify DBFIND, DBGET, DBUPDATE, DBPUT, and DBDELETE
Table 4-2. Database Access Mode Summary
Access
Mode
Type of Access
Mode Granted
Concurrent Access
Modes Allowed
Special
Requirements
1 Modify 1, 5 Modify
(with
locking)
Locking must be used for update
or modify.
2 Update 2, 6 Update
3 Modify None Exclusive Access
4 Modify 6 Read
5 Read 1, 5 Modify
(with
locking)
TurboIMAGE/XL does not require
locking, but it should be used to
coordinate access with users who
are modifying the database.
6 Read 2, 4, 6, 8 Modify
7 Read None Exclusive Access
8 Read 6, 8 Read