What is logical file format?

A logical file determines how data records are selected and defined when read by an application program. A logical file can be a simple, multiple format, or join logical file. A multiple format logical file either contains more than one record format or has more than one file specified on the PFILE keyword.

What is the difference between physical file and logical file in as400?

Physical files contain the actual data that is stored on the system, and a description of how data is to be presented to or received from a program. They contain only one record format, and one or more members. Logical files do not contain data. They contain a description of records found in one or more physical files.

What is record format in as400?

The specific combination of data types and sizes and the number and order of columns is hashed into a value that is known as the “record format identifier”. A significant purpose is the inclusion by compilers of the “record format identifier” in compiled program objects for use when the related file is opened.

How do you create a logical file?

Creating Physical and Logical files in AS400

Create a Physical File. To create a physical database file, enter your source statements in a DDS source file member.
Create a Physical File With Key Fields.
Create a Logical File To Resequence Order of Records.
Create a Logical File To Select and Resequence Records.

Is file a logical storage or physical storage?

Physical (disk) storage contains all the files in the database. Logical storage structures, such as tablespaces, segments, extents, and blocks, appear on the disk but are not part of the dataset. A book serves as a helpful analogy for the difference between physical and logical storage.

What is physical file in as400?

A physical file is a database file that contains data records. The data records are grouped into physical file members and each member has its own access path to the data. Usually, database files have only one member which, by default, is added to the file when the file is created.

Can we update join logical file?

You cannot change a physical file through a join logical file. To do update, delete, or write (add) operations, you must create a second multiple format logical file and use it to change the physical files. You can also use the physical files, directly, to do the change operations.

How do you create a physical file?

To create a physical file, follow these steps:

If you are using DDS, enter DDS for the physical file into a source file. You can do this using the source entry utility (SEU).
Create the physical file. You can use the Create Physical File (CRTPF) command or the Create Source Physical File (CRTSRCPF) command.

What is the definition of a multiple format logical file?

A multiple-format logical file is defined over two or more physical files and, as its name implies, includes more than one record format within the logical file. Each record format is usually associated with a different physical file; the record formats define the data that is included from the physical files.

How to make a multiformat logical file keyed?

Get the names of all the physical files and their record formats that you are combining. Decide what field or fields you are going to use as key to the multiformat logical file. All multiformat logicals must be keyed. Write the DDS and compile it using the CRTLF command to create the file.

How to select multiple records in a logical file?

ü Multiple record format Non-join logical file: 1 Multiple record non-join logical files will select records from 2 or more physical files by referring to only one logical file. 2 Each record format is always associated with one or more physical file. 3 The same PF can be used in more than one record format.

Which is the RPG code for multiple format logicals?

For example, many address records or orders may be associated with each customer. The RPG code for this type of access is SETLL and a READE loop. You can simplify the program code by defining either a multiple-format logical file or a join logical file.

What is logical file format? A logical file determines how data records are selected and defined when read by an application program. A logical file can be a simple, multiple format, or join logical file. A multiple format logical file either contains more than one record format or has more than one file specified on…