26.1.9.1. What is a Data Source Name?
A data source is a place where data comes
from. The data source must have a persistent identifier, the
Data Source Name. Using the Data Source Name, MySQL can access
initialization information. With the initialization information,
MySQL knows where to access the database and what settings to
use when the access starts.
In effect, the data source is the path to
the data. In different contexts this might mean different
things, but typically it identifies a running MySQL server (for
example via a network address or service name), plus the default
database for that server at connection time, plus necessary
connection information such as the port. The MySQL drivers (and,
on Windows systems, the ODBC Driver Manager) use the data source
for connecting. An administrative utility called the Microsoft
ODBC Data Source Administrator may be useful for this purpose.
There are two places where the initialization information might
be: in the Windows registry (on a Windows system), or in a DSN
file (on any system).
If the information is in the Windows registry, it is called a
Machine data source. It might be a
User data source, in which case only one
user can see it. Or it might be a System data
source in which case it is accessible to all users
on the computer, or indeed to all users connected to the
computer, if the users are connected by Microsoft Windows NT
services. When you run the ODBC Data Administration program, you
have a choice whether to use "User" or "System" -- there are
separate tabs.
If the information is in a DSN file, it is called a "File data
source". This is a text file. Its advantages are: (a) it is an
option for any kind of computer, not just a computer with a
Windows operating system; (b) its contents can be transmitted or
copied relatively easily.
