Data source name

Two kinds of DSN exist: • Machine DSNs – stored in collective configuration files (e.g., , ) and/or system resources (e.g., Windows Registry ) • 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., , ) • User DSNs – accessible only by the user who created the DSN, stored in a user-specific location (e.g., , ) == 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: Dim DatabaseObject1 Set DatabaseObject1 = Server.CreateObject("ADODB.Connection") DatabaseObject1.Open("DSN=example;") 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: require_once("DB.php"); //$dsn = "://:@:/"; $dsn = "mysql://john:pass@localhost:3306/my_db"; $db = DB::connect($dsn); PHP with PDO: $dsn = "mysql:host=localhost;dbname=example"; $dbh = new PDO($dsn, $username, $password); In Perl, using the Perl 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. my $dsn = "DBI:Pg:database=finance;host=db.example.com;port=$port"; $dsn = "DBI:mysql:database=$database;host=$hostname;port=$port"; $dsn = "DBI:Oracle:host=$host;sid=$sid;port=$port"; $dsn = "DBI:SQLite:dbname=$dbfilename"; my $dbh = DBI->connect($dsn,'username','password'); == See also ==