Hey all,

So I just came back to this and have come up with a solution, I'm no SQL wizard so I'm not sure how efficient the query actually is but it works!

The following script does require you to know the propertyTypeId of your custom properties (you could change this for the alias of course) and what column the value is stored in.

SELECT
MAX(CASE WHEN pd.propertyTypeId = 50 THEN pd.varcharValue else '' END) AS FirstName,
MAX(CASE WHEN pd.propertyTypeId = 51 THEN pd.varcharValue else '' END) AS LastName,
MAX(CASE WHEN pd.propertyTypeId = 52 THEN pd.varcharValue else '' END) AS Avatar
FROM
dbo.cmsMemberType AS mt 
INNER JOIN dbo.cmsPropertyType AS pt ON mt.propertytypeId = pt.id
INNER JOIN dbo.umbracoPropertyData AS pd ON pt.id = pd.propertytypeid
INNER JOIN dbo.umbracoContentVersion AS ucv ON ucv.id = pd.versionId
GROUP BY ucv.id

With the above script I was able to return the custom member property values for registered members (FirstName, LastName, Avatar)

If you think that there could be any improvements or have any questions please let me know and I hope this helps someone in the same situation as me!