How to modify the value of a field is equal to a field in another table

Update a table field value is equal to the value of a field in another table
Update A
SET a.ty2 = b.ty1
from t2 A, B t1
WHERE a.n2 = b.n1
updated table t2 t1 ty2 field value table ty1 value of the field, with the proviso that a sheet table n1 n2 = b