iX V6.5 (30391-90011)

Chapter 4 93

Using the Database

Opening the Database

4 Using the Database

After you design the database, create the root ﬁle, and build the data sets, you can write

application programs to enter and use the data. Programs written in BBASIC, C,

COBOL II, FORTRAN 77, or Pascal gain access to the database through calls to

TurboIMAGE/XL procedures. RPG programs contain speciﬁcations used by the Report

Program Generator to make calls to the TurboIMAGE/XL procedures for you. This chapter

contains a text discussion of the procedures used to open the database and to enter, read,

update, and delete data; it also contains information on locking, transaction logging,

checking procedure status, and interpreting errors. Use this chapter with chapter 5 which

gives details about each procedure call, its parameters, and status information.

NOTE

Before application programs can be executed, the database must be created

using the TurboIMAGE/XL utility program DBUTIL described in chapter 8.

Opening the Database

Before you can gain access to the data, the process you are running must open the

database with a call to the DBOPEN procedure. A process is a unique execution of a

particular program by a particular user at a particular time, as described in the MPE/iX

Intrinsics Reference Manual. In opening a database, DBOPEN establishes an access path

between the database and your program by doing the following:

• Verifying your right to use the database under the security provisions provided by the

MPE/iX ﬁle system and the TurboIMAGE/XL user-class-password scheme.

• Determining that the access mode you have requested in opening the database is

compatible with the access modes of other users currently using the database.

• Opening the root ﬁle and constructing the control blocks to be used by all other

TurboIMAGE/XL procedures when they are executed. The root ﬁle remains open until

the database is closed.

Note that DBOPEN does not open the individual data sets that compose a database.

DBOPEN also determines if the operating system supports the native language as deﬁned in

the root ﬁle. The following error message is returned if the language attribute of the

database is not supported by the current system conﬁguration:

Language is not supported

Refer to Chapter 6 for more information on Host Language Access and appendix A for

more information on error messages.