Ok, I assume your key field in both tables is the name and the name is equal in both tables. Maybe this could solve your problem (little bit tricky SQL-statement):
SELECT z2~name, z2~birth, z2~mark2, z1~mark1 && z2~mark2 AS total
FROM ztable2 AS z2 INNER JOIN ztable1 AS z1 ON z2~name = z1~name
INTO TABLE @data(lt_z2).
UPDATE ztable2 FROM TABLE lt_z2.