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24/july/2000 - Harbour MySQL access classes - readme file
This is work in progress, so it has to be fully tested and needs a few more methods to cover MySQL possibilities.
This set of files gives you a mean to access a MySQL server, I've developed and tested them on a OS/2 platform,
so changes to Makefile and import library for different platforms are not present.
In their present state MySQL classes are made up of these files:
mysql.c: low level wrapper around MySQL client API. It requires libmysqlclient.a library
mysql.h,
mysql_com.h,
mysql_version.h: from MySQL distribution, type and defines of MySQL client api (under OS/2 with OS/2 port of
MySql you need to use the one from 3.21.33b build which is the only one with a single
threaded libmysqlclient.a client library and works ok even with latest MySQL/2 availble).
mysql.ch: clipper level defines of MySQL types
tmysql.prg: MySQL access classes
test.prg: a little test program which wont work for you :-) since it uses a .dbf file not
provided. Use it as a small tutorial of tmysql.prg provided functions.
Makefile: my makefile for OS/2 gcc, you'll surely need to change it to adapt to your needs/platform.
tmysql.prg defines four classes:
TMySQLServer: manages access to a MySQL server and returns an oServer object to which you'll send all your
queries;
TMySQLQuery: a standard query to an oServer with joins. Every query has a GetRow() method
which on every call returns a TMySQLRow object which, in turn, contains requested fields.
Query objects convert MySQL answers (which is an array of strings) to clipper level types.
At present time N (with decimals), L, D, and C clipper types are supported.
TMySQLTable: It's a descendant of a TMySQLQuery and you'll receive it when your query has no joins.
It adds Update(), Append() and Delete() methods which receive a TMySQLRow object and
reflect changes to the MySQL table from which they come.
Please note that TMySQLQuery objects don't have these methods, so, if you want to change
a row received from a TMySQLQuery object you need to construct a valid SQL query and submit
it to an oServer object.
TMySQLRow: Every row returned by a SELECT is converted to a TMySQLRow object. This object handles
fields and has methods to access fields given a field name or position.
I'm aware that this brief document doesn't explain a lot about MySQL access classes and I'm sorry for that.
I'll try to update it as work on these classes goes by and I'll like to receive feedbak and suggestions
from users (if any :-))
Excuse my poor english and happy selecting :-)
Maurilio Longo - maurilio.longo@libero.it
