AS/400 BPCS difference between files with L01 and the files without (example ILI and ILIL01)

45 pts.
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AS/400
Query
In many queries after the filename L01 is used. Is this to get only the active records? Or can someone explain me what it means?

Thank you!

Rgds,

 

 

 

 

ASKED: May 7, 2010  7:16 AM
UPDATED: May 7, 2010  8:39 PM

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In general, a suffix like “L01″ would indicate a logical file (LF) built over the physical file (PF) that is named the same as first part of the LF name. “L01″ would be the first LF over that PF.

A LF is similar to a SQL VIEW or INDEX. A PF is similar to a SQL TABLE.

Some LFs might be defined in a way that returns only “active records”. Or the definition might be intended only to provide a particular index sequence for sorting or for randomly reading records by key values.

Use DSPFD to see the details of the ILIL01 file description. Use DSPFFD ILIL01to see details of the file field descriptions.

Tom

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  • David40
    Thank you very much Tom! May I ask what you mean with DSPFD and DSPFFD? I like to develop queries in BPCS AS/400, but I don't have much information about it. Like I am searching for a digital copy of a complete Query User Manual for BPCS AS/400. Thank you very much for your help and I am glad I found this page! Bye. David
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  • TomLiotta
    May I ask what you mean with DSPFD and DSPFFD? The nature of your question had me thinking on a slightly different level. I'll fill in background. Those are two command-line commands that provide some materialized views of file objects. The operating systems of the AS/400 line are all "object-based". Files like ILI and ILIL01 are "objects" that are of type *FILE. ILI is a derived sub-type known as a physical file, while ILIL01is a logical file. The system itself generally prohibits access to the internals of any object except through well defined "methods". To see an external view of how the file object ILIL01has its attributes set, use the DSPFD command. Commands generally have a consistent naming structure that indicates what kind of action will be taken and what kind of object that action will operate against. A command that begins with 'DSP' will perform a 'display' action. The 'F' indicates that a file of some kind will be displayed. The 'D' indicates that the description of the file will be displayed. There are often additional parameters that may be specified, for example, to direct the displayed data to the screen, to a printer or to an output file. The default for any DSP command will usually be to output to the screen. So, on a command line, type:
    DSPFD  ILI
    ...and press <Enter>. The command is executed and the description is displayed on the screen. The DSPFFD command displays 'File Field Descriptions'. That means that the description of the fields (or columns) of the file are displayed. You might use this to see which fields from the physical file are exposed by the logical file as well as what the fields are defined as in the logical file. (Field types might be manipulated for convenience or for special purposes.) When any command is entered, the system tries to execute it in your current environment. The DSPFD ILI command might fail because your environment does not include the library (kind of like a SCHEMA or even like a database name in some ways) for ILI. If so, you might need to modify the file name parameter to qualify ILI with a library name. If the ILI file existed in a library named MYBPCS, you might need to type:
    DSPFD  MYBPCS/ILI
    Parameters have some qualities that can become more apparent if you press the <F4=Prompt> key instead of pressing <Enter> after typing the command. When you type the name of a command, possibly including one or more potential parameter values, you can call up the command prompter with the <F4> key. The command prompter brings all kinds of extra assistance. It can show you all of the possible parameters, perhaps all of the possible values of all parameters, the types of values that each parameter can accept (e.g., numeric, dates, names, etc.), the default values for parameters you don't specify, help text to explain what the command does and what each parameter is for... lots of stuff. Along with <F4>, the <F1=Help> key is an almost required key to learn about. Move the cursor almost anywhere on almost any system screen and press <F1> to see some degree of help text that explains whatever was under or near the cursor. This even includes help that explains what all of the various <Fxx> keys are for on any screen that you are looking at. (Even the 'help' displays have <Fxx> keys that can do things for you.) System screens usually have lots of useful help. Application screens, however, may have none. That's completely up to the programmer who wrote it. Anyway, DSPFD displays basic info about a file description. DSPFFD is about field descriptions. DSPFD for a logical file can tell you about any index that might be defined by that file or about any selection criteria, e.g., 'A'ctive records, that might limit which records are accessed. If fields are shown being referenced in the file description, you might review the file field descriptions to see what that field is defined as. Probably much more than you wanted to know, but it can't hurt to say it one place. Tom
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