SQL 显示职位代码、职位描述和担任每个职位的员工人数

时间：2021-04-06 17:08:00

标签： sql

这是我对我的项目的 sql 查询，这是我第一次参加 SQL 课程，我几乎卡住了。

--CREATE DATABASE constructCo; 
--use constructCo; 

CREATE TABLE PROJECT 
(
    PROJ_NUM varchar(3),
    PROJ_NAME varchar(25),
    PROJ_VALUE float(8),
    PROJ_BALANCE float(8)
);

INSERT INTO PROJECT VALUES('15','Evergreen','1453500','1002350');
INSERT INTO PROJECT VALUES('18','Amber Wave','3500500','2110346');
INSERT INTO PROJECT VALUES('22','Rolling Tide','805000','500345.2');
INSERT INTO PROJECT VALUES('25','Starflight','2650500','2309880');

CREATE TABLE EMPLOYEE 
(
    EMP_NUM varchar(3),
    EMP_LNAME varchar(15),
    EMP_FNAME varchar(15),
    EMP_INITIAL varchar(1),
    EMP_HIREDATE date,
    JOB_CODE varchar(3)
);

INSERT INTO EMPLOYEE VALUES('101','Bay','Jackson','F','11/8/2000','502');
INSERT INTO EMPLOYEE VALUES('102','Senior','David','H','7/12/1989','501');
INSERT INTO EMPLOYEE VALUES('103','Arbough','June','E','12/1/1996','503');
INSERT INTO EMPLOYEE VALUES('104','Ramoras','Anne','K','11/15/1987','501');
INSERT INTO EMPLOYEE VALUES('105','Johnson','Alice','K','2/1/1993','502');
INSERT INTO EMPLOYEE VALUES('106','Smithfield','William','','6/22/2004','500');
INSERT INTO EMPLOYEE VALUES('107','Alonzo','Maria','D','10/10/1993','500');
INSERT INTO EMPLOYEE VALUES('108','Washington','Ralph','B','8/22/1991','501');
INSERT INTO EMPLOYEE VALUES('109','Smith','Larry','W','7/18/1997','501');
INSERT INTO EMPLOYEE VALUES('110','Olenko','Gerald','A','12/11/1995','505');
INSERT INTO EMPLOYEE VALUES('111','Wabash','Geoff','B','4/4/1991','506');
INSERT INTO EMPLOYEE VALUES('112','Smithson','Darlene','M','10/23/1994','507');
INSERT INTO EMPLOYEE VALUES('113','Joenbrood','Delbert','K','11/15/1996','508');
INSERT INTO EMPLOYEE VALUES('114','Jones','Annelise','','8/20/1993','508');
INSERT INTO EMPLOYEE VALUES('115','Bawangi','Travis','B','1/25/1992','501');
INSERT INTO EMPLOYEE VALUES('116','Pratt','Gerald','L','3/5/1997','510');
INSERT INTO EMPLOYEE VALUES('117','Williamson','Angie','H','6/19/1996','509');
INSERT INTO EMPLOYEE VALUES('118','Frommer','James','J','1/4/2005','510');

CREATE TABLE ASSIGNMENT 
(
    ASSIGN_NUM int,
    ASSIGN_DATE date,
    PROJ_NUM varchar(3),
    EMP_NUM varchar(3),
    ASSIGN_CHG_HR float(8),
    ASSIGN_HOURS float(8)
);

INSERT INTO ASSIGNMENT VALUES('1001','3/22/2012','18','103','84.5','3.5');
INSERT INTO ASSIGNMENT VALUES('1002','3/22/2012','22','117','34.55','4.2');
INSERT INTO ASSIGNMENT VALUES('1003','3/22/2012','18','117','34.55','2');
INSERT INTO ASSIGNMENT VALUES('1004','3/22/2012','18','103','84.5','5.9');
INSERT INTO ASSIGNMENT VALUES('1005','3/22/2012','25','108','96.75','2.2');
INSERT INTO ASSIGNMENT VALUES('1006','3/22/2012','22','104','96.75','4.2');
INSERT INTO ASSIGNMENT VALUES('1007','3/22/2012','25','113','50.75','3.8');
INSERT INTO ASSIGNMENT VALUES('1008','3/22/2012','18','103','84.5','0.9');
INSERT INTO ASSIGNMENT VALUES('1009','3/23/2012','15','115','96.75','5.6');
INSERT INTO ASSIGNMENT VALUES('1010','3/23/2012','15','117','34.55','2.4');
INSERT INTO ASSIGNMENT VALUES('1011','3/23/2012','25','105','105','4.3');
INSERT INTO ASSIGNMENT VALUES('1012','3/23/2012','18','108','96.75','3.4');
INSERT INTO ASSIGNMENT VALUES('1013','3/23/2012','25','115','96.75','2');
INSERT INTO ASSIGNMENT VALUES('1014','3/23/2012','22','104','96.75','2.8');
INSERT INTO ASSIGNMENT VALUES('1015','3/23/2012','15','103','84.5','6.1');
INSERT INTO ASSIGNMENT VALUES('1016','3/23/2012','22','105','105','4.7');
INSERT INTO ASSIGNMENT VALUES('1017','3/23/2012','18','117','34.55','3.8');
INSERT INTO ASSIGNMENT VALUES('1018','3/23/2012','25','117','34.55','2.2');
INSERT INTO ASSIGNMENT VALUES('1019','3/24/2012','25','104','110.5','4.9');
INSERT INTO ASSIGNMENT VALUES('1020','3/24/2012','15','101','125','3.1');
INSERT INTO ASSIGNMENT VALUES('1021','3/24/2012','22','108','110.5','2.7');
INSERT INTO ASSIGNMENT VALUES('1022','3/24/2012','22','115','110.5','4.9');
INSERT INTO ASSIGNMENT VALUES('1023','3/24/2012','22','105','125','3.5');
INSERT INTO ASSIGNMENT VALUES('1024','3/24/2012','15','103','84.5','3.3');
INSERT INTO ASSIGNMENT VALUES('1025','3/24/2012','18','117','34.55','4.2');

CREATE TABLE EMP_CA 
(
    EMP_NUM varchar(3),
    EMP_LNAME varchar(15),
    EMP_FNAME varchar(15),
    EMP_INITIAL varchar(1),
    EMP_HIREDATE date,
    JOB_CODE varchar(3)
);

INSERT INTO EMP_CA VALUES('101','News','John','G','11/8/2000','502');
INSERT INTO EMP_CA VALUES('102','Senior','David','H','7/12/1989','501');
INSERT INTO EMP_CA VALUES('103','Arbough','June','E','12/1/1996','500');
INSERT INTO EMP_CA VALUES('104','Ramoras','Anne','K','11/15/1987','501');
INSERT INTO EMP_CA VALUES('106','Smithfield','William','','6/22/2004','500');
INSERT INTO EMP_CA VALUES('107','Alonzo','Maria','D','10/10/1993','500');
INSERT INTO EMP_CA VALUES('108','Washington','Ralph','B','8/22/1991','501');

CREATE TABLE EMP_US 
(
    EMP_NUM varchar(3),
    EMP_LNAME varchar(15),
    EMP_FNAME varchar(15),
    EMP_INITIAL varchar(1),
    EMP_HIREDATE date,
    JOB_CODE varchar(3)
);

INSERT INTO EMP_US VALUES('101','News','John','G','11/8/2000','502');
INSERT INTO EMP_US VALUES('103','Arbough','June','E','12/1/1996','500');
INSERT INTO EMP_US VALUES('105','Johnson','Alice','K','2/1/1993','502');
INSERT INTO EMP_US VALUES('107','Alonzo','Maria','D','10/10/1993','500');
INSERT INTO EMP_US VALUES('109','Smith','Larry','W','7/18/1997','501');

CREATE TABLE JOB 
(
    JOB_CODE varchar(3),
    JOB_DESCRIPTION varchar(25),
    JOB_CHG_HOUR float(8)
);

INSERT INTO JOB VALUES('500','Programmer','35.75');
INSERT INTO JOB VALUES('501','Systems Analyst','96.75');
INSERT INTO JOB VALUES('502','Database Designer','125');
INSERT INTO JOB VALUES('503','Electrical Engineer','84.5');
INSERT INTO JOB VALUES('504','Mechanical Engineer','67.9');
INSERT INTO JOB VALUES('505','Civil Engineer','55.78');
INSERT INTO JOB VALUES('506','Clerical Support','26.87');
INSERT INTO JOB VALUES('507','DSS Analyst','45.95');
INSERT INTO JOB VALUES('508','Applications Designer','48.1');
INSERT INTO JOB VALUES('509','Bio Technician','34.55');
INSERT INTO JOB VALUES('510','General Support','18.36');

我需要创建的查询也在标题中，但这里是“显示职位代码、职位描述和担任每个职位的员工人数。”

我尝试了一些聚合函数和子查询，例如 count 和 have，但我就是想不通

如果有人可以提供帮助，我将不胜感激。

谢谢！

1 个答案:

答案 0 :(得分：0)

这就是您想要的，也许有更好的解决方案，但行数更少，但这可以给您一些想法：

SELECT JOB_CODE, JOB_DESCRIPTION, COUNT(*) AS EmpCount FROM
(
    SELECT JOB.JOB_CODE, JOB_DESCRIPTION FROM EMPLOYEE
    JOIN JOB ON EMPLOYEE.JOB_CODE = JOB.JOB_CODE

    UNION ALL

    SELECT JOB.JOB_CODE, JOB_DESCRIPTION FROM EMP_CA 
    JOIN JOB ON EMP_CA.JOB_CODE = JOB.JOB_CODE

    UNION ALL

    SELECT JOB.JOB_CODE, JOB_DESCRIPTION FROM EMP_US
    JOIN JOB ON EMP_US.JOB_CODE = JOB.JOB_CODE
) x
GROUP BY JOB_CODE, JOB_DESCRIPTION
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