1.2.3 Database Operation
The DLI library performs the database operations issued from MPP or BMP programs. It can retrieve and hold one specific segment according the specified segment search criteria, updates a specific segment, inserts a segment at a specific position, deletes a specific segment, etc. Detailed APIs for database operation are listed in the following table 9.
Table 1-10 Database Operation Processes and Commands
| Name | Description |
|---|---|
GU/GHU
|
Retrieves (and Holds) the first segment that satisfies the criteria (if any) from the current position (if any) or the beginning of the database. |
GN/GHN
|
Retrieves (and Holds) the next segment that satisfies the criteria (if any) from current position. |
GNP/GHNP
|
Retrieves (and Holds) the next segment that satisfies the criteria from the dependent segments of the established parent. |
ISRT
|
Used to insert a new occurrence of an existing segment type into a hierarchy database. |
REPL
|
Used to update an existing segment. |
DLET
|
Used to remove a segment and its dependents. |
FLD
|
Used to access a field within a segment. |
POS
|
A qualified Position (POS) call is used to retrieve the location of a specific sequential dependent segment. An unqualified POS points to the logical end of the sequential dependent segment (SDEP) data. |
OPEN
|
Used to explicitly open a GSAM database. |
CLSE
|
Used to explicitly close a GSAM database. |