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For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Checking the database connection manually

For an initial database connectivity test from my own code, I use the mysql client program and 'check out' the commands manually through that. Noting all the parameters, I then check through a piece of code in my target language ... in this brief example from Wednesday, it was Perl:

use DBI;
 
# From my manual test:
# mysql -h192.168.200.84 -utrainee -pabc123
# use wellho
# select agid,locate,sid from sales
 
$db_handle = DBI ->
  connect("DBI:mysql:wellho:192.168.200.84","trainee","abc123")
    or die ("connection failed: $DBI::errstr\n");
 
$qu_handle = $db_handle -> prepare("select agid,locate,sid from sales");
$qu_handle -> execute;
 
while (@row = $qu_handle -> fetchrow()) {
  print "@row\n";
  }

One of the most common questions I get by email from people I have never heard of before relates to getting 3rd Party software running on their own systems. And one of the most common solutions that I suggest is checking out their database connection - changing sample MySQL accounts from user "hello" and password "world" to the name of an account that exists on their system ;-). A short test such as the one above, and done with the knowledge of what each step is doing, can identify these initial connection problems very quickly indeed.
(written 2009-08-28)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
S156 - Interfacing Applications to MySQL Databases
  [104] mysql_connect or mysql_pconnect in PHP? - (2004-10-30)
  [644] Using a MySQL database from Perl - (2006-03-13)
  [663] Python to MySQL - (2006-03-31)
  [723] Viewing images held in a MySQL database via PHP - (2006-05-17)
  [1381] Using a MySQL database to control mod_rewrite via PHP - (2007-10-06)
  [1450] Easy selection of multiple SQL conditions from PHP - (2007-11-30)
  [1518] Downloading data for use in Excel (from PHP / MySQL) - (2008-01-25)
  [1561] Uploading to a MySQL database through PHP - examples and common questions - (2008-03-02)
  [1885] Hiding a MySQL database behind a web page - (2008-11-15)
  [2263] Mysqldump fails as a cron job - a work around - (2009-06-30)
  [2745] Connecting Python to sqlite and MySQL databases - (2010-04-28)
  [2790] Joining a MySQL table from within a Python program - (2010-06-02)
  [3035] How to display information from a database within a web page - (2010-11-07)
  [3099] Perl - database access - DBD, DBI and DBIx modules - (2010-12-22)
  [3447] Needle in a haystack - finding the web server overload - (2011-09-18)
  [3455] MySQL, MySQLi, PDO or something else - how best to talk to databases from PHP - (2011-09-24)
  [4436] Accessing a MySQL database from Python with mysql.connector - (2015-02-21)

P308 - Using SQL Databases from Perl
  [515] MySQL - an FAQ - (2005-12-03)
  [975] Answering ALL the delegate's Perl questions - (2006-12-09)
  [1224] Object Relation Mapping (ORM) - (2007-06-09)
  [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
  [2561] The future of MySQL - (2010-01-03)


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Giving up on user input - keyboard timeout in Perl
Some other Articles
Reading all our recent news from a single source
Looking ahead to the Autumn season of training and accommodation
Lua Regular Expressions
Giving up on user input - keyboard timeout in Perl
Checking the database connection manually
Object Oriented programming - a practical design example
Making variables persistant, pretending a database is a variable and other Perl tricks
Handling XML in Perl - introduction and early examples
Wiltshire / Melksham Weddings - guest accommodation
Long job - progress bar techniques (Perl)
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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