Data source name: Difference between revisions

Revision as of 05:47, 17 May 2018

Revision as of 01:35, 28 July 2018

Line 8:

* the ___location of the data source

* the name of a [[database driver]] which can access the data source

* a [[User identifier | user ID]] for data access (if required)

* a user password for data access (if required)

Line 18:

Two kinds of DSN exist:

* '''Machine DSNs''' -– stored in collective configuration files (e.g., /etc/odbc.ini, ~/.odbc.ini) and/or system resources (e.g., Windows Registry HKLM\Software\ODBC\odbc.ini)

* '''File DSNs''' -– stored in the filesystem with one DSN per file

These are further broken down into

* '''System DSNs''' -– accessible by any and all processes and users of the system, stored in a centralized ___location (e.g., /etc/odbc.ini, /etc/odbc_file_dsns/<filename>)

* '''User DSNs''' -– accessible only by the user who created the DSN, stored in a user-specific ___location (e.g., ~/.odbc.ini, ~/odbc_file_dsns/<filename>)

== Example of use ==

Software (e.g., Crystal Reports, Microsoft Excel, PHP, Perl, Python, Ruby) users can submit CRUD (Create, Read, Update, Delete) queries to a data source by establishing a connection to the DSN.

ASP ([[VBScript]]) code to open a DSN connection might look like the following:

<sourcesyntaxhighlight lang="vb">

Dim DatabaseObject1

Set DatabaseObject1 = Server.CreateObject("ADODB.Connection")

DatabaseObject1.Open("DSN=example;")

</syntaxhighlight>

</source>

In [[PHP]] using the PEAR::DB package to open a connection without an external DSN (a "DSN-less connection", i.e., using a Connection String), the code might resemble the following

<sourcesyntaxhighlight lang="php">

require_once("DB.php");

//$dsn = "<driver>://<username>:<password>@<host>:<port>/<database>";

$dsn = "mysql://john:pass@localhost:3306/my_db";

$db = DB::connect($dsn);

</sourcesyntaxhighlight>{{Clarifyme|How is this an example of DSN use|date=June 2013}}

PHP with PDO.

<sourcesyntaxhighlight lang="php">

$dsn = "mysql:host=localhost;dbname=example";

$dbh = new PDO($dsn, $username, $password);

</syntaxhighlight>

</source>

In [[Perl]], using the [[Perl_DBIPerl DBI]] module, each driver has its own syntax for the DSN attributes. The only requirement that DBI makes is that all the information, except for username and password is supplied in a single string argument.

<sourcesyntaxhighlight lang="perl">

my $dsn = "DBI:Pg:database=finance;host=db.example.com;port=$port";

$dsn = "DBI:mysql:database=$database;host=$hostname;port=$port";

Line 60:

my $dbh = DBI->connect($dsn,'username','password');

</syntaxhighlight>

</source>

== See also ==

* [[Datasource]]

* [[ADO.NET]]

Line 72:

[[Category:Data access technologies| ]]

{{database-stub}}