1.題目描述

查找各個部門當前(to_date='9999-01-01')領導當前薪水詳情以及其對應部門編號dept_no

CREATE TABLE `dept_manager` ( `dept_no` char(4) NOT NULL, `emp_no` int(11) NOT NULL, `from_date` date NOT NULL, `to_date` date NOT NULL, PRIMARY KEY (`emp_no`,`dept_no`)); CREATE TABLE `salaries` ( `emp_no` int(11) NOT NULL, `salary` int(11) NOT NULL, `from_date` date NOT NULL, `to_date` date NOT NULL, PRIMARY KEY (`emp_no`,`from_date`)); INSERT INTO dept_manager VALUES('d001',10002,'1996-08-03','9999-01-01'); INSERT INTO dept_manager VALUES('d002',10006,'1990-08-05','9999-01-01'); INSERT INTO dept_manager VALUES('d003',10005,'1989-09-12','9999-01-01'); INSERT INTO dept_manager VALUES('d004',10004,'1986-12-01','9999-01-01'); INSERT INTO dept_manager VALUES('d005',10010,'1996-11-24','2000-06-26'); INSERT INTO dept_manager VALUES('d006',10010,'2000-06-26','9999-01-01'); INSERT INTO salaries VALUES(10001,60117,'1986-06-26','1987-06-26'); INSERT INTO salaries VALUES(10001,62102,'1987-06-26','1988-06-25'); INSERT INTO salaries VALUES(10001,66074,'1988-06-25','1989-06-25'); INSERT INTO salaries VALUES(10001,66596,'1989-06-25','1990-06-25'); INSERT INTO salaries VALUES(10001,66961,'1990-06-25','1991-06-25'); INSERT INTO salaries VALUES(10001,71046,'1991-06-25','1992-06-24'); INSERT INTO salaries VALUES(10001,74333,'1992-06-24','1993-06-24'); INSERT INTO salaries VALUES(10001,75286,'1993-06-24','1994-06-24'); INSERT INTO salaries VALUES(10001,75994,'1994-06-24','1995-06-24'); INSERT INTO salaries VALUES(10001,76884,'1995-06-24','1996-06-23'); INSERT INTO salaries VALUES(10001,80013,'1996-06-23','1997-06-23'); INSERT INTO salaries VALUES(10001,81025,'1997-06-23','1998-06-23'); INSERT INTO salaries VALUES(10001,81097,'1998-06-23','1999-06-23'); INSERT INTO salaries VALUES(10001,84917,'1999-06-23','2000-06-22'); INSERT INTO salaries VALUES(10001,85112,'2000-06-22','2001-06-22'); INSERT INTO salaries VALUES(10001,85097,'2001-06-22','2002-06-22'); INSERT INTO salaries VALUES(10001,88958,'2002-06-22','9999-01-01'); INSERT INTO salaries VALUES(10002,72527,'1996-08-03','1997-08-03'); INSERT INTO salaries VALUES(10002,72527,'1997-08-03','1998-08-03'); INSERT INTO salaries VALUES(10002,72527,'1998-08-03','1999-08-03'); INSERT INTO salaries VALUES(10002,72527,'1999-08-03','2000-08-02'); INSERT INTO salaries VALUES(10002,72527,'2000-08-02','2001-08-02'); INSERT INTO salaries VALUES(10002,72527,'2001-08-02','9999-01-01'); INSERT INTO salaries VALUES(10003,40006,'1995-12-03','1996-12-02'); INSERT INTO salaries VALUES(10003,43616,'1996-12-02','1997-12-02'); INSERT INTO salaries VALUES(10003,43466,'1997-12-02','1998-12-02'); INSERT INTO salaries VALUES(10003,43636,'1998-12-02','1999-12-02'); INSERT INTO salaries VALUES(10003,43478,'1999-12-02','2000-12-01'); INSERT INTO salaries VALUES(10003,43699,'2000-12-01','2001-12-01'); INSERT INTO salaries VALUES(10003,43311,'2001-12-01','9999-01-01'); INSERT INTO salaries VALUES(10004,40054,'1986-12-01','1987-12-01'); INSERT INTO salaries VALUES(10004,42283,'1987-12-01','1988-11-30'); INSERT INTO salaries VALUES(10004,42542,'1988-11-30','1989-11-30'); INSERT INTO salaries VALUES(10004,46065,'1989-11-30','1990-11-30'); INSERT INTO salaries VALUES(10004,48271,'1990-11-30','1991-11-30'); INSERT INTO salaries VALUES(10004,50594,'1991-11-30','1992-11-29'); INSERT INTO salaries VALUES(10004,52119,'1992-11-29','1993-11-29'); INSERT INTO salaries VALUES(10004,54693,'1993-11-29','1994-11-29'); INSERT INTO salaries VALUES(10004,58326,'1994-11-29','1995-11-29'); INSERT INTO salaries VALUES(10004,60770,'1995-11-29','1996-11-28'); INSERT INTO salaries VALUES(10004,62566,'1996-11-28','1997-11-28'); INSERT INTO salaries VALUES(10004,64340,'1997-11-28','1998-11-28'); INSERT INTO salaries VALUES(10004,67096,'1998-11-28','1999-11-28'); INSERT INTO salaries VALUES(10004,69722,'1999-11-28','2000-11-27'); INSERT INTO salaries VALUES(10004,70698,'2000-11-27','2001-11-27'); INSERT INTO salaries VALUES(10004,74057,'2001-11-27','9999-01-01'); INSERT INTO salaries VALUES(10005,78228,'1989-09-12','1990-09-12'); INSERT INTO salaries VALUES(10005,82621,'1990-09-12','1991-09-12'); INSERT INTO salaries VALUES(10005,83735,'1991-09-12','1992-09-11'); INSERT INTO salaries VALUES(10005,85572,'1992-09-11','1993-09-11'); INSERT INTO salaries VALUES(10005,85076,'1993-09-11','1994-09-11'); INSERT INTO salaries VALUES(10005,86050,'1994-09-11','1995-09-11'); INSERT INTO salaries VALUES(10005,88448,'1995-09-11','1996-09-10'); INSERT INTO salaries VALUES(10005,88063,'1996-09-10','1997-09-10'); INSERT INTO salaries VALUES(10005,89724,'1997-09-10','1998-09-10'); INSERT INTO salaries VALUES(10005,90392,'1998-09-10','1999-09-10'); INSERT INTO salaries VALUES(10005,90531,'1999-09-10','2000-09-09'); INSERT INTO salaries VALUES(10005,91453,'2000-09-09','2001-09-09'); INSERT INTO salaries VALUES(10005,94692,'2001-09-09','9999-01-01'); INSERT INTO salaries VALUES(10006,43311,'1990-08-05','1991-08-05'); INSERT INTO salaries VALUES(10006,43311,'1991-08-05','1992-08-04'); INSERT INTO salaries VALUES(10006,43311,'1992-08-04','1993-08-04'); INSERT INTO salaries VALUES(10006,43311,'1993-08-04','1994-08-04'); INSERT INTO salaries VALUES(10006,43311,'1994-08-04','1995-08-04'); INSERT INTO salaries VALUES(10006,43311,'1995-08-04','1996-08-03'); INSERT INTO salaries VALUES(10006,43311,'1996-08-03','1997-08-03'); INSERT INTO salaries VALUES(10006,43311,'1997-08-03','1998-08-03'); INSERT INTO salaries VALUES(10006,43311,'1998-08-03','1999-08-03'); INSERT INTO salaries VALUES(10006,43311,'1999-08-03','2000-08-02'); INSERT INTO salaries VALUES(10006,43311,'2000-08-02','2001-08-02'); INSERT INTO salaries VALUES(10006,43311,'2001-08-02','9999-01-01'); INSERT INTO salaries VALUES(10007,56724,'1989-02-10','1990-02-10'); INSERT INTO salaries VALUES(10007,60740,'1990-02-10','1991-02-10'); INSERT INTO salaries VALUES(10007,62745,'1991-02-10','1992-02-10'); INSERT INTO salaries VALUES(10007,63475,'1992-02-10','1993-02-09'); INSERT INTO salaries VALUES(10007,63208,'1993-02-09','1994-02-09'); INSERT INTO salaries VALUES(10007,64563,'1994-02-09','1995-02-09'); INSERT INTO salaries VALUES(10007,68833,'1995-02-09','1996-02-09'); INSERT INTO salaries VALUES(10007,70220,'1996-02-09','1997-02-08'); INSERT INTO salaries VALUES(10007,73362,'1997-02-08','1998-02-08'); INSERT INTO salaries VALUES(10007,75582,'1998-02-08','1999-02-08'); INSERT INTO salaries VALUES(10007,79513,'1999-02-08','2000-02-08'); INSERT INTO salaries VALUES(10007,80083,'2000-02-08','2001-02-07'); INSERT INTO salaries VALUES(10007,84456,'2001-02-07','2002-02-07'); INSERT INTO salaries VALUES(10007,88070,'2002-02-07','9999-01-01'); INSERT INTO salaries VALUES(10008,46671,'1998-03-11','1999-03-11'); INSERT INTO salaries VALUES(10008,48584,'1999-03-11','2000-03-10'); INSERT INTO salaries VALUES(10008,52668,'2000-03-10','2000-07-31'); INSERT INTO salaries VALUES(10009,60929,'1985-02-18','1986-02-18'); INSERT INTO salaries VALUES(10009,64604,'1986-02-18','1987-02-18'); INSERT INTO salaries VALUES(10009,64780,'1987-02-18','1988-02-18'); INSERT INTO salaries VALUES(10009,66302,'1988-02-18','1989-02-17'); INSERT INTO salaries VALUES(10009,69042,'1989-02-17','1990-02-17'); INSERT INTO salaries VALUES(10009,70889,'1990-02-17','1991-02-17'); INSERT INTO salaries VALUES(10009,71434,'1991-02-17','1992-02-17'); INSERT INTO salaries VALUES(10009,74612,'1992-02-17','1993-02-16'); INSERT INTO salaries VALUES(10009,76518,'1993-02-16','1994-02-16'); INSERT INTO salaries VALUES(10009,78335,'1994-02-16','1995-02-16'); INSERT INTO salaries VALUES(10009,80944,'1995-02-16','1996-02-16')

元數據展示：?

結果展示：

第一種寫法：?

select s.*,d.dept_no from salaries s,dept_manager d where s.emp_no = d.emp_no and s.to_date = d.to_date and s.to_date = '9999-01-01'

第二種寫法：

select s.*,d.dept_no from salaries s join dept_manager d on s.emp_no = d.emp_no where d.to_date = '9999-01-01' and s.to_date = '9999-01-01';

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有親身去寫的會發現在不寫s.to_date = d.to_date，也可以。但是為什么還要寫上呢？

select s.*,d.dept_no from salaries s,dept_manager d where s.emp_no = d.emp_no and s.to_date = '9999-01-01'

為了去重鎖定！！！

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2.題目描述

查找所有已經分配部門的員工的last_name和first_name

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 `employees` ( `emp_no` int(11) NOT NULL, `birth_date` date NOT NULL, `first_name` varchar(14) NOT NULL, `last_name` varchar(16) NOT NULL, `gender` char(1) NOT NULL, `hire_date` date NOT NULL, PRIMARY KEY (`emp_no`));

數據：?

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,'d004','1995-12-03','9999-01-01'); INSERT INTO dept_emp VALUES(10004,'d004','1986-12-01','9999-01-01'); INSERT INTO dept_emp VALUES(10005,'d003','1989-09-12','9999-01-01'); INSERT INTO dept_emp VALUES(10006,'d002','1990-08-05','9999-01-01'); INSERT INTO dept_emp VALUES(10007,'d005','1989-02-10','9999-01-01'); INSERT INTO dept_emp VALUES(10008,'d005','1998-03-11','2000-07-31'); INSERT INTO dept_emp VALUES(10009,'d006','1985-02-18','9999-01-01'); INSERT INTO dept_emp VALUES(10010,'d005','1996-11-24','2000-06-26'); INSERT INTO dept_emp VALUES(10010,'d006','2000-06-26','9999-01-01'); INSERT INTO employees VALUES(10001,'1953-09-02','Georgi','Facello','M','1986-06-26'); INSERT INTO employees VALUES(10002,'1964-06-02','Bezalel','Simmel','F','1985-11-21'); INSERT INTO employees VALUES(10003,'1959-12-03','Parto','Bamford','M','1986-08-28'); INSERT INTO employees VALUES(10004,'1954-05-01','Chirstian','Koblick','M','1986-12-01'); INSERT INTO employees VALUES(10005,'1955-01-21','Kyoichi','Maliniak','M','1989-09-12'); INSERT INTO employees VALUES(10006,'1953-04-20','Anneke','Preusig','F','1989-06-02'); INSERT INTO employees VALUES(10007,'1957-05-23','Tzvetan','Zielinski','F','1989-02-10'); INSERT INTO employees VALUES(10008,'1958-02-19','Saniya','Kalloufi','M','1994-09-15'); INSERT INTO employees VALUES(10009,'1952-04-19','Sumant','Peac','F','1985-02-18'); INSERT INTO employees VALUES(10010,'1963-06-01','Duangkaew','Piveteau','F','1989-08-24'); INSERT INTO employees VALUES(10011,'1953-11-07','Mary','Sluis','F','1990-01-22');

?兩種寫法：

select e.first_name,e.last_name,d.dept_no from employees e,dept_emp d where e.emp_no = d.emp_no and d.dept_no is not nullselect e.last_name,e.first_name,d.dept_no from employees e left join dept_emp d on e.emp_no = d.emp_no where d.dept_no is not null;

自我認為重點在于? ?is not null

https://georgedage.blog.csdn.net/article/details/103466057

?

總結

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