iX V6.5 (30391-90011)

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Chapter 4 129

Using the Database

Obtaining Database Structure Information

The DBINFO library procedure allows you to acquire information programmatically about

the database. It provides information about database settings, data items, data sets, data

paths, B-Tree indices, and third-party indices. The information returned is restricted by

the user class number and access mode established when the database is opened.

Any data items, data sets, or paths of the database inaccessible to that user class or in that

access mode are considered to be non-existent. For example, if the access mode grants only

read access, this procedure will indicate that no data sets can have entries added. The

information that can be obtained through separate calls to DBINFO is summarized below.

In relation to data items, DBINFO can be used to:

• Determine whether the user class number established when the database is opened

allows a speciﬁed data item value to be changed in at least one data set, or allows a data

entry containing the item to be added or deleted.

• Get a description of a data item including the data item name, type, sub-item length,

and sub-item count. This information corresponds to that which is speciﬁed in the item

part of the schema.

• Determine the number of items in the database available to the current user and to get

a list of numbers identifying those items. The numbers indicate the position of each

data item in the item part of the schema. The type of access, for example read-only, can

also be determined.

• Determine the number of items in a particular data set available to the current user

and get a list of those item numbers and the type of access available for each one.

In relation to data sets, DBINFO can be used to:

• Determine whether the current user can add or delete entries to a particular data set.

• Get a data set description including the data set name, type, length in halfwords and

blocking factor for data entries in the set, number of entries in the set, and the capacity.

• Determine the number of data sets the current user can access and get a list of the data

set numbers indicating the position of the data set deﬁnition in the set part of the

schema. The type of access to each set is also indicated.

• Determine in which data sets a particular data item is available to the current user.

The number of data sets, a list of data set numbers, and the type of access available for

each set is returned.

• Obtain capacity information. Determine if a data set is jumbo, and if so, information on

chunks.

• Determine if master data set has a B-Tree index.

In relation to paths, DBINFO can be used to:

• Get information about the paths associated with a particular data set including the

number of paths. If the data set is a master set, the information includes the data set

number, search item number, and sort item number for each related detail. If the data