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)


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Reading all our recent news from a single source
Looking ahead to the Autumn season of training and accommodation
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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
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