Database-Description Statements

The following statements define the IMS database in an access descriptor.
DATABASE=database-name DBTYPE=database-type;
RECORD=record-name SEGMENT=segment-name
GROUP=group-name LEVEL=level-number
KEY=Y | N | U OCCURS=number-of-repeats
ITEM=item-name LEVEL=level-number
FORMAT=SAS-format SEARCH=search-name
KEY=Y | N | U OCCURS=number-of-repeats
DELETE item-name | index-number;
INSERT item-name | index-number;
REPLACE item-name | index-number;
The DATABASE=, RECORD=, and ITEM= statements are required to create an access descriptor with the CREATE statement; the GROUP= statement is optional. The INSERT, DELETE, and REPLACE statements are used with the UPDATE statement to change an existing access descriptor. At least one of the GROUP=, RECORD=, or ITEM= statements must be used with the INSERT, DELETE, and REPLACE statements to change an access descriptor. The DATABASE= statement cannot be used in an UPDATE statement.
Whether you are creating or changing an access descriptor, the RECORD=, ITEM=, and GROUP= statements must be used in the same order as they appear in the database.
Because IMS does not have a dictionary or store descriptive information about the database, you need to provide the DBD information. To provide this information, you need to have a COBOL copybook or layout of the database.
For logical databases, the access descriptor definitions are mapped to the logical DBD and not to one or more physical DBDs. This enables the IMS engine to build correct calls and for the SSAs (segmented search arguments) to navigate the logical structure of the database.
Note: See Tools for Creating IMS Access Descriptors for tools that SAS supplies to automate the database definition process.