Help With Subquery And Having Clause ..
Apr 28, 2008Hey, I'm referencing a database about a fictitious IT company, and I'm trying to answer the following statement:
Determine who has logged the most hours. Create a SELECT statement to return their name and the max hours they have worked. NOTE: This is a tougher one but looking into using a Subquery and use the HAVING statement.
I've written this so far, and although it does give me the right answer (there is only one employee in the DB who has worked on projects) it is not entirely correct. Basically there is no subquery, and it doesn't really show who has worked the max hours:
SELECT
EMPLOYEE_NAME 'Employee Name', SUM(HOURS_LOGGED) 'Maximum Hours Logged'
FROM
PROJECT_EMPLOYEE PE
INNER JOIN
PROJECT_HOURS PH ON PH.EMPLOYEE_ID = PE.EMPLOYEE_ID
INNER JOIN
PROJECT P ON P.PROJECT_ID = PH.PROJECT_ID
GROUP BY
PE.EMPLOYEE_NAME
Here is the DB if needed:
CREATE TABLE project_employee (
employee_id INT,
employee_name VARCHAR(40),
employee_hire_date DATETIME,
employee_termination_date DATETIME,
employee_billing_rate INT,
CONSTRAINT project_employee_pk
PRIMARY KEY (employee_id)
);
CREATE TABLE project (
project_id INT,
project_name VARCHAR(40),
project_budget INT,
CONSTRAINT project_pk
PRIMARY KEY (project_id)
);
CREATE TABLE project_hours (
project_id INT,
employee_id INT,
time_log_date DATETIME,
hours_logged INT,
dollars_charged INT,
CONSTRAINT project_hours_pk
PRIMARY KEY (project_id, employee_id, time_log_date),
CONSTRAINT proj_hours_fkto_projectemployee
FOREIGN KEY (employee_id) REFERENCES project_employee,
CONSTRAINT proj_hours_fkto_project
FOREIGN KEY (project_id) REFERENCES project
);
INSERT INTO project
(project_id, project_name, project_budget)
VALUES (1001, 'Corporate Web Site',1912000);
INSERT INTO project
(project_id, project_name, project_budget)
VALUES (1002, 'Year 2000 Fixes',999998000);
INSERT INTO project
(project_id, project_name, project_budget)
VALUES (1003, 'Accounting System Implementation',897000);
INSERT INTO project
(project_id, project_name, project_budget)
VALUES (1004, 'Data Warehouse Maintenance',294000);
INSERT INTO project
(project_id, project_name, project_budget)
VALUES (1005, 'TCP/IP Implementation',415000);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (101, 'Jonathan Gennick','15-Nov-1961',null,169);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (102, 'Jenny Gennick','16-Sep-1964','5-May-1998',135);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (104, 'Jeff Gennick','29-Dec-1987','1-Apr-1998',99);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (105, 'Horace Walker','15-Jun-1998',null,121);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (107, 'Bohdan Khmelnytsky', '2-Jan-1998',null,45);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (108, 'Pavlo Chubynsky','1-Mar-1994','15-Nov-1998',220);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (110, 'Ivan Mazepa', '4-Apr-1998','30-Sep-1998',84);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (111, 'Taras Shevchenko', '23-Aug-1976',null,100);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (112, 'Hermon Goche', '15-Nov-1961','4-Apr-1998',70);
INSERT INTO project_employee
(employee_id, employee_name, employee_hire_date,
employee_termination_date, employee_billing_rate)
VALUES (113, 'Jacob Marley', '3-Mar-1998','31-Oct-1998',300);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1001,101,'01-JAN-1998',1.00,169.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1003,101,'01-JAN-1998',3.00,507.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1005,101,'01-JAN-1998',5.00,845.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1002,101,'01-FEB-1998',7.00,1183.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1004,101,'01-FEB-1998',1.00,169.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1001,101,'01-MAR-1998',3.00,507.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1003,101,'01-MAR-1998',5.00,845.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1005,101,'01-MAR-1998',7.00,1183.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1002,101,'01-APR-1998',1.00,169.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1004,101,'01-APR-1998',3.00,507.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1001,101,'01-MAY-1998',5.00,845.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1003,101,'01-MAY-1998',7.00,1183.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1005,101,'01-MAY-1998',1.00,169.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1002,101,'01-JUN-1998',3.00,507.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1004,101,'01-JUN-1998',5.00,845.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1001,101,'01-JUL-1998',7.00,1183.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1003,101,'01-JUL-1998',1.00,169.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1005,101,'01-JUL-1998',3.00,507.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1002,101,'01-AUG-1998',5.00,845.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1004,101,'01-AUG-1998',7.00,1183.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1001,101,'01-SEP-1998',1.00,169.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1003,101,'01-SEP-1998',3.00,507.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1005,101,'01-SEP-1998',5.00,845.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1002,101,'01-OCT-1998',7.00,1183.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1004,101,'01-OCT-1998',1.00,169.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1001,101,'01-NOV-1998',3.00,507.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1003,101,'01-NOV-1998',5.00,845.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1005,101,'01-NOV-1998',7.00,1183.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1002,101,'01-DEC-1998',1.00,169.00);
INSERT INTO project_hours (project_id, employee_id, time_log_date, hours_logged, dollars_charged)
VALUES (1004,101,'01-DEC-1998',3.00,507.00);