Report writer can arrange the data in accordance with the instructions in the REPORT program block or in the report driver and to perform the output. The output can be sent:
to the screen
to a file
to a printer
to a pipe
To be able to write a report a program must have two components:
REPORT program block that formats the report output
The report driver that invokes and processes the report
The report driver contains the statements that retrieve rows from a database, store their values in program variables and send them to the report. The information is sent to the report in portions called the input records, after the last such record has been received and formatted by the REPORT program block, the aggregate values based on these records are calculated, if required. After that, the report is sent to the output device.
The fact that the processed of data retrieval and data formatting are separated makes it easier to apply the same report to different sets of data.