diff --git a/models/group/group_team.go b/models/group/group_team.go
new file mode 100644
index 0000000000..7080832146
--- /dev/null
+++ b/models/group/group_team.go
@@ -0,0 +1,42 @@
+package group
+
+import (
+	"code.gitea.io/gitea/models/db"
+	"context"
+)
+
+// GroupTeam represents a relation for a team's access to a group
+type GroupTeam struct {
+	ID      int64 `xorm:"pk autoincr"`
+	OrgID   int64 `xorm:"INDEX"`
+	TeamID  int64 `xorm:"UNIQUE(s)"`
+	GroupID int64 `xorm:"UNIQUE(s)"`
+}
+
+// HasTeamGroup returns true if the given group belongs to team.
+func HasTeamGroup(ctx context.Context, orgID, teamID, groupID int64) bool {
+	has, _ := db.GetEngine(ctx).
+		Where("org_id=?", orgID).
+		And("team_id=?", teamID).
+		And("group_id=?", groupID).
+		Get(new(GroupTeam))
+	return has
+}
+
+func AddTeamGroup(ctx context.Context, orgID, teamID, groupID int64) error {
+	_, err := db.GetEngine(ctx).Insert(&GroupTeam{
+		OrgID:   orgID,
+		GroupID: groupID,
+		TeamID:  teamID,
+	})
+	return err
+}
+
+func RemoveTeamGroup(ctx context.Context, orgID, teamID, groupID int64) error {
+	_, err := db.DeleteByBean(ctx, &GroupTeam{
+		TeamID:  teamID,
+		GroupID: groupID,
+		OrgID:   orgID,
+	})
+	return err
+}
diff --git a/models/group/group_unit.go b/models/group/group_unit.go
new file mode 100644
index 0000000000..89b3c131cf
--- /dev/null
+++ b/models/group/group_unit.go
@@ -0,0 +1,25 @@
+package group
+
+import (
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/perm"
+	"code.gitea.io/gitea/models/unit"
+	"context"
+)
+
+// GroupUnit describes all units of a repository group
+type GroupUnit struct {
+	ID         int64     `xorm:"pk autoincr"`
+	GroupID    int64     `xorm:"INDEX"`
+	TeamID     int64     `xorm:"UNIQUE(s)"`
+	Type       unit.Type `xorm:"UNIQUE(s)"`
+	AccessMode perm.AccessMode
+}
+
+func (g *GroupUnit) Unit() unit.Unit {
+	return unit.Units[g.Type]
+}
+
+func getUnitsByGroupID(ctx context.Context, groupID int64) (units []*GroupUnit, err error) {
+	return units, db.GetEngine(ctx).Where("group_id = ?", groupID).Find(&units)
+}