GroupMembership Table

The GroupMembership table stores a list of the principals that are members of each site group in a site collection. The GroupMembership table is defined using T-SQL syntax, as follows.

 TABLE GroupMembership(
       SiteId                         uniqueidentifier   NOT NULL,
       GroupId                        int                NOT NULL,
       MemberId                       int                NOT NULL

SiteId: The site collection identifier (section of the site collection containing the principals and site groups.

GroupId: The group identifier of the site group that the principal specified by MemberId is a member of.

MemberId: The user identifier (section of a principal that is a member of the site group specified by GroupId.