there are two tables involved

DNN4_ProfilePropertyDefinition, associates a PropertyDefinitionID with the rest of the property description.

DNN4_UserProfile has properties for each UserID with the PropertyDefinitionID only.

Here is a way to get a value based on the property name:

SELECT @street = P.PropertyValue
FROM {objectQualifier}UserProfile P
JOIN {objectQualifier}ProfilePropertyDefinition D on P.PropertyDefinitionID = D.PropertyDefinitionID
and D.PropertyName = 'Street'

This was from Charlie at Beldin Technologies, who has a PDF report generator and was helping me build some queries for reports.

note, I only know about 4.3, so if you are using an earlier version, I have not ever looked at those tables.  It does include all properties as far as I know.  It contained the custom properties i created.

go into the SQL query and paste some of these queries...

/* get list of users and IDs */
SELECT * FROM DNN4_Users

/* get all the data for a specific user */
SELECT * FROM DNN4_UserProfile
WHERE UserID = 4

/* get the list of properties and their IDs */
SELECT * FROM DNN4_ProfilePropertyDefinition

/* get the information, including the ID for a specific property, can be more than one for some... */
SELECT * FROM DNN4_ProfilePropertyDefinition
WHERE PropertyName = 'FirstName'

hope this helps