From the environment variable, you can use the get_database() function to connect to any database that is supported by Chameleon:

environment.get_database(DatabaseType, DatabaseName, UserName, Password)

This function returns a database object that enables you to query a database and obtain data from it.

	It is important to note that the connection that get_database() establishes to a database is not inside a transaction envelope. Actions performed on this database cannot be safely rolled back.

The four parameters that the get_database() function requires are all strings. The only parameter that is not self-explanatory is the DatabaseType parameter. The table below lists the possible values for this parameter and when you should use each one.

For a simple example of how to use get_database(), suppose that you have a MySQL database named patient_info that contains a table named addresses. This table contains two columns: PatientName, which is the surname of a patient, and PatientAddress, which is the patient's address.

Now, suppose that your Chameleon VMD file contains a table named Patient that contains three columns:

• Name, which is the patient's surname, and which is mapped from PID.5.1.1 (the first sub-subfield of the first subfield of field 5 of the PID segment);
• ID, which is mapped from PID.3.1 (the first subfield of field 3 of the PID segment);
• Address, which is not mapped from any field in a segment. This field will be populated by the PatientAddress field of the patient_info database.

To populate the Address field of this table, you must modify your VMD file to query the patient_info database. To do this:

• Ensure that database support is enabled for Python. To do this, select Options from the Chameleon toolbar, click the DB tab, and complete the fields displayed. For more information on the DB tab, see the description of the DB tab.
• Create the following Segment Inbound script for field 5 of the PID segment:

# replace "userid" and "password" with your own userid and password
db = environment.get_database("MySQL", "patient_info", "userid", "password")
query = 'SELECT * FROM addresses WHERE PatientName="' + value + '"'
results = db.execute_select(query)
if results.count_of_row() > 0:
     Address = results.value(0, "PatientAddress")
else:
     Address = "unknown"

	If you have not enabled database support for Python, the call to db.execute_select() will return 1, and this script will not work.

• In the Address column of the Patient table, create the following Table Inbound script:

value = Address

The Segment Inbound script retrieves the patient address from the MySQL database and assigns it to a Python global variable named Address. (It assumes that there is only one database entry that matches; if more than one match is found, it chooses the first match.) The Table Inbound script then sets the value of the Address field of the Patient table to be the of the Address global variable.

	For more information on the database object returned by get_database(), see Database Object.