I you want to get a list of all groups and the members in a site collection you can use this sql script.
Replace the SITE GUID with the guid of site collection for which you want this list
tp_title AS [User name],
tp_Email as [Mail address],
Title as [SharePoint group]
INNER JOIN UserInfo ON GroupMembership.MemberID=UserInfo.tp_ID and GroupMembership.SiteID=UserInfo.tp_SiteID
INNER JOIN Groups ON GroupMembership.GroupID=Groups.ID and GroupMembership.SiteID=Groups.SiteId