CREATE TABLE room (blockfloor VARCHAR(255), blockcode VARCHAR(255)); CREATE TABLE BLOCK (blockcode VARCHAR(255), blockfloor VARCHAR(255))
Find the number of rooms for different block code?
    
SQL: SELECT COUNT(*), T1.blockcode FROM BLOCK AS T1 JOIN room AS T2 ON T1.blockfloor = T2.blockfloor AND T1.blockcode = T2.blockcode GROUP BY T1.blockcode