Avg for past x months weekly

Hi, below is my data tables I have.

table1:

sku_id dateval sales_data
ab124 20210603 10
ab124 20210502 20
ab123 20210606

30

table2:

date_val yr_num yr_wk_num day_wk_num yr_wk_nm day mo_num
20200808 2020 32 6 202032 Saturday 08
20200809 2020 32 7 202032 Sunday 08
20200810 2020 33 1 202033 Monday 08
20200811 2020 33 2 202033 Tuesday 08
20200812 2020 33 3 202033 Wednesday 08

I need to take week number from table 2 comparing dateval from table1 and date_val in table 2 and do the below scenarios in looker.

  1. Rolling avg for 6 months weekly
  2. Same week prior year sales

Am new to looker. please suggest me how to achieve these scenarios in looker (LExp or view).