"Examples are either simple as to be trivial, or too complex to understand" said a delegate - so this afternoon I accepted his challenge to come up with some thing in between. And the example is for some MySQL table design and design testing, with a Perl program to access and tabulate the data.

Scenario - A table of CUSTOMERS each of whom has a number of order REQUESTS each of which includes a number of line ITEMS. (3 tables so far!) A table of STORES each of which has a number of AISLES, each of which has a number of different PRODUCTS on it. That's six tables now. The items table contains a product id column, so that all the tables can be linked together.


Customer, request, item tables


Store, aisle, product tables

# Note - all fields start with same letter in each table
# Note - all tables have a unique id field
# Note - all tables first letter in unique
# Note - all table names are singular
# Note - sample data includes 2 records at each level so
# that we can test the dynamics but keep it as simple as poss
(Don't you love comments - those come from the test file!)

Here are the results of various reports:



Here is the "base" query behind all the joins and reports:

select c_name,p_name,i_count,p_price,a_name,s_name from
((store
join aisle on sid = a_sid)
join product on aid = p_aid)
join
((customer
join request on cid = r_cid )
join item on rid=i_rid)
on pid = i_pid ;

and you can see all the code used here. The output is here.

Finally - the Perl program's source is here.
(written 2007-11-06 16:35:12)

 S154 - MySQL - Designing an SQL Database System

Back to Wiltshire - speaker / after dinner talker offer

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Arrays in Tcl - a demonstration
Buffering up in Tcl - the empty coke can comparison
Melksham v Ely
Closer than you think - the next step
MySQL - table design and initial testing example
Wiltshire - speaker / after dinner talker offer
Castle Lodge Hotel, Ely, Cambridgeshire
The Learning Perl crew, October 2007
National Speaker - now to get the talk ready
A Golf Club Decision - Perl to Java
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