统计所有课程参加培训人次

drop table if exists  `staff_tb` ; 
CREATE TABLE `staff_tb` (
`staff_id` int(11) NOT NULL,
`staff_name` varchar(16) NOT NULL,
`staff_gender` char(8) NOT NULL,
`post` varchar(11) NOT NULL,
`department` varchar(16) NOT NULL,
PRIMARY KEY (`staff_id`));
INSERT INTO staff_tb VALUES(1,'Angus','male','Financial','dep1'); 
INSERT INTO staff_tb VALUES(2,'Cathy','female','Director','dep1'); 
INSERT INTO staff_tb VALUES(3,'Aldis','female','Director','dep2'); 
INSERT INTO staff_tb VALUES(4,'Lawson','male','Engineer','dep1'); 
INSERT INTO staff_tb VALUES(5,'Carl','male','Engineer','dep2'); 
INSERT INTO staff_tb VALUES(6,'Ben','male','Engineer','dep1'); 
INSERT INTO staff_tb VALUES(7,'Rose','female','Financial','dep2'); 

drop table if exists  `cultivate_tb` ;   
CREATE TABLE `cultivate_tb` (
`info_id` int(11) NOT NULL,
`staff_id` int(11) NOT NULL,
`course` varchar(32) NULL,
PRIMARY KEY (`info_id`));
INSERT INTO cultivate_tb VALUES(101,1,'course1,course2');
INSERT INTO cultivate_tb VALUES(102,2,'course2');
INSERT INTO cultivate_tb VALUES(103,3,'course1,course3');
INSERT INTO cultivate_tb VALUES(104,4,'course1,course2,course3');
INSERT INTO cultivate_tb VALUES(105,5,'course3');
INSERT INTO cultivate_tb VALUES(106,6,NULL);
INSERT INTO cultivate_tb VALUES(107,7,'course1,course2');

staff_nums
11