I have to build a logic to update one column SC_LEVI_LVL IN GCC_MAST.CLNT_MAST based on the match found on the below criteria:

(I am just looking at the select clause and I will update it later using update strategy in informatica)

The Joins needs to be made on three tables:

for Priority 1 the join needs to be made on below two tables:

GCC_LANDING.CB_AT_LIS CB
    GCC_MAST.CLNT_MAST TM

For Priority 2 the join needs to be made on below 3 tables:

GCC_LANDING.CB_AT_LIS CB
GCC_MAST.CLNT_MAST TM
GCC_LANDING.GRID_MATRIX GM

PRIORITY 1:

CB.REL_COUNTRY=TM.REL_COUNTRY
AND CB.GRID=TM.GRID
WHERE TM.SCH_LEG_ENTY NOT LIKE '