Sample help file - PHP example

PHP and MySQL example application - adhoc database analysis example from a Well House Consultants training course
More on PHP and MySQL example application - adhoc database analysis [link]

Source code: help1.txt Module: H204

Ad Hoc Query tool for SQL
With an SQL Query, there are certain elements (such as
which tables are joined to which other tables, and on
which fields) which are naturally fixed, and other
elements (such as which columns are wanted on the
output, and which rows are to be chosen) which may
vary from one query to another - especially in an
application where a database is being used to store
large amounts of data gathered for statistical analysis.
 
This demonstration program, written for training
purposed by Graham Ellis of Well House Consultants,
allows a standard query to be embedded into a
configuration file that can't be altered by the
user, and then allows the user to select which rows
and columns are required on the report. The
configuration file also allows the specification of
what inputs the user has in making selections -
columns can be turned on or off by default, and the
criteria for row selection can also be limited.
 
If you want to try out this demo, you may do
so; we've loaded it onto this website at
<a href=/adhoc/adhoc_sql_query_engine.php>
/adhoc/adhoc_sql_query_engine.php</a>
and it's got a login name of "demo" with a password of
"xxx111".. If you would like to see the source
code of all the files, there are links to
them from <a href=/resources/H204.html>the module
description</a>
<hr>
System Overview
This demonstration is based on a 4 layer model, keeping
the main application, web helper routines, business logic
and HTML templates each in its own file. The top layer
is the file adhoc_sql_query_engine.php and you'll find
that it 
1. Establishes / picks up the current session 
2. Checks inputs made on the form just enters 
3. Decides which is the next form 
4. Prepares for the next form 
5. Completes and sends out the next template 
All pages in the system are numbered - and that number
is tracked in the variable $current. A simple run
of the system would be: 
Page 1 - Login 
Page 10 - Select a default or tuned query 
Page 11 - Select the ROWS you want 
Page 12 - Select the COLUMNS you want 
Page 20 - Display results 
Page 199 - Logout 
You'll go straight from page 10 to page 20 if you select
the default query, and you're able to jump back from page
20 to page 10 if you want to run a series of queries
without logging in many times over. <nr>
Extensions 
If this demonstration was extended, logins would be
validated against a database (and not just hard coded)
and perhaps there would be a "lost password" system
too.

Learn about this subject

This example is covered on the following public courses:
* Learning to program in PHP
* PHP Programming
and is fully described on the course or in your printed course manual

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