PHP makes use of variables, arrays, and functions. But can you tell them apart?

Written by David Shirey

In my last column, we talked about some of the special operator symbols that PHP uses, which can be really confusing when you read PHP unless you're familiar with them. Remember what they were? Remember the -< operator? Really, you do? That's so sad then because there is no such operator (at least as far as I know, although I would hate to put any serious money on it; PHP operators seem to just come up out of the cracks).

Find out by using the Retrieve Product Information (QSZRTVPR) API.

Written by Bruce Vining

A question that seems to come up on a regular basis is "How can a program tell what release level of the operating system it's running on?" To answer this question, we'll look at a category of system APIs that many of you may not have reviewed in the past—the Software Product APIs, which are introduced here.

The IFS is a great place to store stream files but it has some serious limitations. This series of articles presents an alternative.

Written by Joe Pluta

Recently, several different requirements ended up colliding in a way that led me to do a lot of research on using Large Objects (LOBs) in my RPG programs. While they require a little bit of extra up-front investment, LOBs provide a way to integrate large-scale use of stream file data into your enterprise system.

Open the door to the OMI program template.

Written by Junlei Li

In a post in the MI400-L mailing list at midrange.com, Simon Coulter documented the Materialize Program (QSCMATPG) and Create Program (QSCCRTPG) APIs in detail, including the parameter lists and related usage notes. Simon also designed a couple of CL commands to make it easier and more secure to use these APIs. With this information, you can open the door to the Original MI (OMI) program template, which allows a System/38 program to survive all the hardware changes and run on the most current IBM i release without recompilation.

When a file contains variable-length fields, the data of the fixed-length fields of its deleted records can still be retrieved.

Written by Juan Macias

A known technique to retrieve the records deleted from a file consists of saving the file to a save file and extracting the records from the save file. This technique is based on the fact that, in many cases, the records of the file are stored in the save file, maintaining their format, apart from a status byte added by the system at the beginning of each record.

Editor's note: This article is an excerpt from Mastering IBM i, published by MC Press.

Written by James Buck and Jerry Fottral

SQL's version of a logical file is a view. Although a view is conceptually similar to a logical file, SQL's greater flexibility and ability to use functions and expressions make views far more powerful than logical files. For example, in a logical file there is no way to select group summary records based on the value returned by a column function, as we did in the final example of the previous article. Nevertheless, in SQL, creating such a view is easy; in fact, we already have most of the code for it. The only thing we need to do is prefix our earlier Select statement with a Create View statement and then name the virtual column created by the Min function. Here is the statement to create the view of department elders:

Online Analytical Processing (OLAP) adds a variety of processing features to SQL syntax that makes it much more useful as an ad hoc analysis tool, and this article introduces the first of those functions.

Written by Joe Pluta

SQL has always been a great tool for querying data. The problem is that SQL doesn't always lend itself to the sort of pattern analysis that's needed in enterprise data processing. Something goes awry in the database and the only way to identify the source of the problem is to backtrack through history. Let me give you a real-world example (the data has been changed to protect the innocent, but the situation is pretty common).

Learn how to ensure the validity of extended character string assignment via the CPYECLAP instruction.

Written by Junlei Li

IMHO, high-level languages (HLLs) in IBM i do not treat character strings containing double-byte character set (DBCS) characters seriously enough. For example, assigning a long character string containing DBCS characters to a shorter character variable using the EVAL operation code of RPG would probably truncate the DBCS data in the source string and therefore lead to an invalid result character string.