Introducing Data-Reading Programs

Definition: Data-reading commands

There is a group of commands, often referred to as data-reading commands, that you can use in programs to read data from external files in various formats: binary, packed decimal, or text. The data-reading commands are described below.

Function or Command	Description
FILEERROR function	Returns information about the first error that occurred when you are processing a record from an input file with the data-reading commands FILEREAD and FILEVIEW.
FILENEXT function	Makes a record available for processing by the FILEVIEW command. It returns YES when it is able to read a record and NO when it reaches the end of the file.
FILEREAD command	Reads records from an input file, processes the data, and stores the data in OLAP DML dimensions, composites, relations, and variables, according to descriptions of the fields in the input record.
FILEVIEW command	Works in conjunction with the FILENEXT function to read one record at a time of an input file, process the data, and store the data in OLAP DML dimensions and variables according to the descriptions of the fields.
RECNO function	Reports the current record number of a file opened for reading.

Description: File I/O commands

You use the data-reading commands with file I/O commands, such as the commands described below.

Function or Command	Description
FILECLOSE command	Closes an open file.
FILEGET function	Returns text from a file that has been opened for reading.
FILEOPEN function	Opens a file, assigns it a fileunit number (an arbitrary integer), and returns that number.
FILEPUT command	Writes data that is specified in a text expression to a file that is opened in WRITE or APPEND mode.
FILEQUERY function	Returns information about one or more files.
FILESET command	Sets the paging attributes of a specified fileunit.

Definition: Data-reading programs

While some of the data-reading commands can be used individually, it is best to place them in a program that is often referred to as a data-reading program. In this way you can minimize mistakes in typing and test your commands on smaller sets of data. A program also allows you to perform operations in which several commands are used together to loop over many records in a file.