question: What is Date, when City / State is "Mallala , South Australia", and when Team is "R.J.MacArthur Onslow"?
answer: SELECT date FROM table_name_19 WHERE city___state = "mallala , south australia" AND team = "r.j.macarthur onslow"
context: CREATE TABLE table_name_19 (date VARCHAR, city___state VARCHAR, team VARCHAR)