DLET command

The Delete (DLET) command is used to remove a segment and its dependents from the database.

Format

Options

USING PCB(expression): Specifies the DB PCB you want to use for the command. Its argument can be any expression that converts to the integer data type; you can specify either a number or a reference to a halfword in your program containing a number.
VARIABLE: Indicates that a segment is variable-length.
SEGMENT(name): Qualifies the command, specifying the name of the segment type you want to retrieve, insert, delete, or replace.
SEGMENT((area)): Is a reference to an area in your program containing the name of the segment type. You can specify an area instead of specifying the name of the segment in the command.
SEGLENGTH(expression): Specifies the length of the I/O area into which the segment is retrieved. Its argument can be any expression that converts to the integer data type; you can specify either a number or a reference to a halfword in your program containing a number. (It is required in COBOL programs for any SEGMENT level that specifies the INTO or FROM option.)
Requirement: The value specified for SEGLENGTH must be greater than or equal to the length of the longest segment that can be processed by this call.
FROM(area): Specifies an area containing the segment to be added, replaced, or deleted. Use FROM to insert one or more segments with one command.
SETZERO(data_value): Specifies setting a subset pointer to zero.

Usage

You use the DLET command to delete a segment and its dependents from the database. You must first retrieve segments you want to delete, just as if you were replacing segments, The DLET command deletes the retrieved segment and its dependents, if any, from the database.

Example

Evelyn Parker has moved away from this area. Her patient number is 10450. Delete her record from the database.

Explanation

You want to delete all the information about Evelyn Parker from the database. To do this, you must delete the PATIENT segment. When you do this, DL/I deletes all the dependents of that segment. This is exactly what you want DL/I to do—there is no reason to keep such segments as ILLNESS and TREATMNT for Evelyn Parker if she is no longer one of the clinic's patients.

Before you can delete the patient segment, you have to retrieve it:

EXEC DLI GU
     SEGMENT(PATIENT) INTO(PATAREA) WHERE (PATNO=PATNO1);

To delete this patient's database record, you issue a DLET command and use the FROM option to give the name of the I/O area that contains the segment you want deleted:

EXEC DLI DLET SEGMENT(PATIENT) FROM(PATAREA);

When you issue this command, the PATIENT segment, and its dependents—the ILLNESS, TREATMNT, BILLING, PAYMENT, and HOUSHOLD segments—are deleted.

Restrictions

You cannot issue any commands using the same PCB between the retrieval command and the DLET command, and you can issue only one DLET command for each GET command.