有一个部门表departments简况如下: dept_no dept_name d001 Marketing d002 Finance 有一个，部门员工关系表dept_emp简况如下: emp_no dept_no from_date to_date 10001 d001 1986-06-26 9999-01-01 10002 d001 1996-08-03 9999-01-01 10003 d002 1995-12-03 9999-01-01 有一个职称表titles简况如下: emp_no title form_date to_date 10001 Senior Engineer 1986-06-26 9999-01-01 10002 Staff 1996-08-03 9999-01-01 10003 Senior Engineer 1995-12-03 9999-01-01 汇总各个部门当前员工的title类型的分配数目，即结果给出部门编号dept_no、dept_name、其部门下所有的员工的title以及该类型title对应的数目count，结果按照dept_no升序排序，dept_no一样的再按title升序排序 dept_no dept_name title count d001 Marketing Senior Engineer 1 d001 Marketing Staff 1 d002 Finance Senior Engineer 1
示例1

输入

drop table if exists  `departments` ; 
drop table if exists  `dept_emp` ; 
drop table if exists  titles ;
CREATE TABLE `departments` (
`dept_no` char(4) NOT NULL,
`dept_name` varchar(40) NOT NULL,
PRIMARY KEY (`dept_no`));
CREATE TABLE `dept_emp` (
`emp_no` int(11) NOT NULL,
`dept_no` char(4) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
CREATE TABLE titles (
`emp_no` int(11) NOT NULL,
`title` varchar(50) NOT NULL,
`from_date` date NOT NULL,
`to_date` date DEFAULT NULL);
INSERT INTO departments VALUES('d001','Marketing');
INSERT INTO departments VALUES('d002','Finance');
INSERT INTO dept_emp VALUES(10001,'d001','1986-06-26','9999-01-01');
INSERT INTO dept_emp VALUES(10002,'d001','1996-08-03','9999-01-01');
INSERT INTO dept_emp VALUES(10003,'d002','1995-12-03','9999-01-01');
INSERT INTO titles VALUES(10001,'Senior Engineer','1986-06-26','9999-01-01');
INSERT INTO titles VALUES(10002,'Staff','1996-08-03','9999-01-01');
INSERT INTO titles VALUES(10003,'Senior Engineer','1995-12-03','9999-01-01');

输出

d001|Marketing|Senior Engineer|1
d001|Marketing|Staff|1
d002|Finance|Senior Engineer|1
加载中...