set serveroutput on --打开sqlplus输出，如果是用plsqldev 这个忽略

DECLARE
  V_CNT INT;
BEGIN
  FOR REC IN (SELECT CODE FROM B) LOOP
    EXECUTE IMMEDIATE 'select count(1) from t_' || REC.CODE
      INTO V_CNT;
    DBMS_OUTPUT.PUT_LINE('表[t_' || REC.CODE || ']数据条数：' || V_CNT);
  END LOOP;
END;

------解决方案--------------------

SQL code

DECLARE
  V_CNT INT;
  V_SUM INT;--总条数。
BEGIN
  V_SUM :=0;      
  FOR REC IN (SELECT CODE FROM B) LOOP
    EXECUTE IMMEDIATE 'select count(1) from t_' || REC.CODE
      INTO V_CNT;
    V_SUM := V_SUM + V_CNT;     
  END LOOP;
END;