Need Help for sum statement

[eluser]Farzand[/eluser]
ok i explain you.
1:- i trying to make reports between to dates
2:- first table is tayyab_lc and his sub table is tayyab_remarks. when i search between dates so first i search in main table and sum weight then get his id and find sub tables and sum remarks. but sub table don`t search between dates.

bt_tayyab_lc table have these fields id,weight,creat_at
bt_tayyab_remarks have these fields id,lcid,remarks,creat_at

i want make relation between these fields but with sum
first search this
bt_tayyab_lc sum(weight) between two dates
then do this
bt_tayyab_lc. id bt_tayyab_remarks. lcid

sum(bt_tayyab_remarks. remarks)

i hope you understand becoz i am new in php forums so i use codeintor to build this webbase lc managment system