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The Carnie_MyCareer Case Study
Peter EbeidDane Harris
Stephanie HoChris Zaharia
Distinction Assignment, Autumn 2007
Presented by
Introduction to Carnie_MyCareer Database
• This database is a simplified version of the 'MyCareer' website.
• It allows prospective job seekers to register and apply for positions. Users may apply for multiple positions, and more than one person may apply for any given job.
The ERD for Carnie_MyCareerLocIDLocCityLocCountry
Location
CanIDCanFirstNameCanLastNameCanSexCanBirthYear
Candidate
SecIDSecTitleSecDesc
Sector
JobID*CanID*AppID
Application
JobIDJobPostDateJobSalaryJobPositionLocID*SecID*JobDesc
Job
SQL Queries on a Single Entity/ Table
Project (using “select”)
• Report a job’s title and salary
SELECT jobposition, jobsalary FROM Carnie_MyCareer_Job;
The columns you listbetween “SELECT” and“FROM” are displayed.
jobposition | jobsalary-------------+----------- Senior | 50000 CFO | 120000 Jr | 45000 Reception | 20000 Graduate | 38000 Team Member | 85000 Team Member | 45000 2IC | 60000 Logistics | 75000
Restrict (using “where”)
• Get all jobs with a salary (jobsalary) greater then 70000
SELECT * FROM Carnie_MyCareer_Job WHERE jobsalary > 70000;
jobid | jobpostdate | jobsalary | jobposition | locid | secid | jobdesc-------+-------------+-----------+-------------+-------+-------+----------------------------------- 2 | 01-01-2005 | 120000 | CFO | 1 | 1 | CFO of big four bank 6 | 25-06-2005 | 85000 | Team Member | 4 | 4 | Help rebuild peoples lives in Iraq 9 | 25-06-2005 | 75000 | Logistics | 4 | 3 | Team player with excellent skills
Project and restrict combo
• You can specify any combination of columns and rows
• Example: List all job’s post date, title and salary where salaries are less then 50000
SELECT jobpostdate, jobsalary, jobposition FROM Carnie_MyCareer_Job WHERE jobsalary < 50000;
jobpostdate | jobsalary | jobposition-------------+-----------+------------- 01-03-2005 | 45000 | Jr 05-03-2005 | 20000 | Reception 07-02-2005 | 38000 | Graduate 25-06-2005 | 45000 | Team Member
IS NULL & IS NOT NULL
• IS NULL
SELECT jobposition, jobsalary FROM Carnie_MyCareer_Job WHERE jobsalary IS NULL;
• IS NOT NULL
SELECT jobposition, jobsalary FROM Carnie_MyCareer_Job
WHERE jobsalary IS NOT NULL;
jobposition | jobsalary ------------+-----------(0 rows)
jobposition | jobsalary-------------+----------- Senior | 50000 CFO | 120000 Jr | 45000 … etc … | … etc …
IN
• Used with a list of values
• Example: Report all jobs where job title is CEO or Team Member
SELECT * FROM Carnie_MyCareer_Job
where jobposition IN ('CEO','Team Member');
jobid | jobpostdate | jobsalary | jobposition | locid | secid | jobdesc-------+-------------+-----------+-------------+-------+-------+----------------------------------- 6 | 25-06-2005 | 85000 | Team Member | 4 | 4 | Help rebuild peoples lives in Iraq 7 | 25-06-2005 | 45000 | Team Member | 5 | 4 | Anti-Terror proofing parlment house
NOT IN
• Not in a list of values
• Report all jobs where job title is other then CEO or Team Member
SELECT * FROM Carnie_MyCareer_Job WHERE jobposition NOT IN ('CEO','Team Member');
jobid | jobpostdate | jobsalary | jobposition | locid | secid | jobdesc-------+-------------+-----------+-------------+-------+-------+----------------------------------- 1 | 01-01-2005 | 50000 | Senior | 1 | 1 | Account manager, blue chip company 2 | 01-01-2005 | 120000 | CFO | 1 | 1 | CFO of big four bank 3 | 01-03-2005 | 45000 | Jr | 1 | 2 | Entry level Database position. Great start!! 4 | 05-03-2005 | 20000 | Reception | 2 | 3 | Basic office admin, phones and coffee making 5 | 07-02-2005 | 38000 | Graduate | 3 | 1 | Great start for a fresh graduate 8 | 25-06-2005 | 60000 | 2IC | 2 | 2 | Second in command of well run NZ IT company 9 | 25-06-2005 | 75000 | Logistics | 4 | 3 | Team player with excellent organisation skills
Ordering columns
SELECT jobsalary, jobposition FROM Carnie_MyCareer_Job WHERE
jobpostdate = '01-01-2005';
SELECT jobposition, jobsalary FROM Carnie_MyCareer_Job WHERE
jobpostdate = '01-01-2005';
jobsalary | jobposition-----------+------------- 50000 | Senior 120000 | CFO
jobposition | jobsalary-------------+----------- Senior | 50000 CFO | 120000
Ordering rows: “order by”
• List all jobs where salary is at least 50000, and order the report in descending order by salary amounts
SELECT * FROM Carnie_MyCareer_Job WHERE jobsalary >= 50000 ORDER BY jobsalary DESC;
Note – DESC is short for Descending
jobid | jobpostdate | jobsalary | jobposition | locid | secid | jobdesc-------+-------------+-----------+-------------+-------+-------+----------------------------------- 2 | 01-01-2005 | 120000 | CFO | 1 | 1 | CFO of big four bank 6 | 25-06-2005 | 85000 | Team Member | 4 | 4 | Help rebuild peoples lives in Iraq 9 | 25-06-2005 | 75000 | Logistics | 4 | 3 | Team player with excellent skills 8 | 25-06-2005 | 60000 | 2IC | 2 | 2 | Second in command of well run NZ IT 1 | 01-01-2005 | 50000 | Senior | 1 | 1 | Account manager, blue chip company
Calculating
• AS
SELECT jobposition, jobsalary, jobsalary*1.3 AS jobsalaryUSD FROM Carnie_MyCareer_Job;
jobposition | jobsalary | jobsalaryusd-------------+-----------+-------------- Senior | 50000 | 65000.0 CFO | 120000 | 156000.0 Jr | 45000 | 58500.0 Reception | 20000 | 26000.0 Graduate | 38000 | 49400.0 Team Member | 85000 | 110500.0 Team Member | 45000 | 58500.0 2IC | 60000 | 78000.0 Logistics | 75000 | 97500.0
AVG, SUM, MIN, and MAX Functions
• Average salary (AVG)
SELECT AVG(jobsalary) FROM Carnie_MyCareer_Job;
• Sum of salaries (SUM)
SELECT SUM(jobsalary) FROM Carnie_MyCareer_Job;
• Minimum salary (MIN)
SELECT MIN(jobsalary) FROM Carnie_MyCareer_Job;
• Maximum salary (MAX)
SELECT MAX(jobsalary) FROM Carnie_MyCareer_Job;
AVG(jobsalary) ---------------
59777.7777778
SUM(jobsalary) --------------
538000
MIN(jobsalary) --------------
20000 MAX(jobsalary)
-------------- 120000
COUNT Function
• Determine the total number of rows in the job table
COUNT(*) : the number of rows
SELECT COUNT(*) FROM Carnie_MyCareer_Job;
OR
• COUNT(name of column) : the number of non-null values in that column
SELECT COUNT(jobsalary) FROM Carnie_MyCareer_Job;
count ------- 9
count ------- 9
LIKE - Pattern matching
• List all job dates starting with the 1st of the month
SELECT jobpostdate FROM Carnie_MyCareer_Job WHERE jobpostdate LIKE '01%';
• List all job dates in March
SELECT jobpostdate FROM Carnie_MyCareer_Job WHERE jobpostdate LIKE '%-03-%';
jobpostdate------------- 01-01-2005 01-01-2005 01-03-2005
jobpostdate------------- 01-03-2005 05-03-2005
LIKE - Pattern matchingList job titles with the 4th letter as “i”
SELECT jobposition FROM Carnie_MyCareer_Job WHERE jobposition LIKE '___i%';
• List all job titles without an “e” in their name
SELECT jobposition FROM Carnie_MyCareer_Job WHERE jobposition NOT LIKE '%E%' AND jobposition NOT LIKE '%e%';
jobposition------------- Senior Logistics
jobposition------------- CFO Jr 2IC Logistics
DISTINCT
• Eliminating duplicate rows
Report the different values of job salaries
SELECT DISTINCT jobsalary FROM Carnie_MyCareer_Job;
The value 45000 does not display twice
jobsalary----------- 20000 38000 45000 50000 60000 75000 85000 120000
Inserting rows
INSERT INTO Carnie_Mycareer_Job (jobid, jobpostdate, jobsalary, jobposition, locid, secid, jobdesc) VALUES (1, '01-01-2005', 50000, 'Senior', 1, 1,'Account manager, blue chip company');
• OR
INSERT INTO Carnie_Mycareer_Job VALUES (1,
'01-01-2005', 50000, 'Senior', 1, 1,'Account manager, blue chip company');
Foreign Keys and Natural Joins
The Natural Join (1)
• Create a new table from two existing tables by matching on common columns
SELECT * FROM Carnie_MyCareer_Job NATURAL JOIN Carnie_MyCareer_Location;
locid | jobid | jobpostdate | jobsalary | jobposition | secid | jobdesc | loccity | loccountry-------+-------+-------------+-----------+-------------+-------+-------------------------------------+------------+------------- 1 | 1 | 01-01-2005 | 50000 | Senior | 1 | Account manager, blue chip company | Sydney | Australia 1 | 2 | 01-01-2005 | 120000 | CFO | 1 | CFO of big four bank | Sydney | Australia 1 | 3 | 01-03-2005 | 45000 | Jr | 2 | Entry level Database position. Great| Sydney | Australia 2 | 4 | 05-03-2005 | 20000 | Reception | 3 | Basic office admin, phones | Wellington | New Zealand 3 | 5 | 07-02-2005 | 38000 | Graduate | 1 | Great start for a fresh graduate | New York | USA 4 | 6 | 25-06-2005 | 85000 | Team Member | 4 | Help rebuild peoples lives in Iraq | Baghdad | Iraq 5 | 7 | 25-06-2005 | 45000 | Team Member | 4 | Anti-Terror proofing parliment house| Canberra | Australia 2 | 8 | 25-06-2005 | 60000 | 2IC | 2 | Second command of well run company | Wellington | New Zealand 4 | 9 | 25-06-2005 | 75000 | Logistics | 3 | Team player with excellent skills | Baghdad | Iraq
The Natural Join (2)
• The same thing as using “natural join” on the previous slide, but using the alternate (“cross product”) notation
SELECT * FROM Carnie_MyCareer_Job, Carnie_MyCareer_Location WHERE Carnie_MyCareer_Job.locid = Carnie_MyCareer_Location.locid;
• Notice the use of the dot ... a table name, followed by “.”, followed by the name of a column in the table. This disambiguates which column we mean.
The Natural Join (2)
• The dot notation is used to disambiguate between columns of the same name in different tables
• Example: Table 1 (Carnie_MyCareer_Job)
• Table 2 (Carnie_MyCareer_Location)
jobid | jobpostdate | jobsalary | jobposition | locid| secid | jobdesc-------+-------------+-----------+-------------+-------+-------+------------------------------------------------ 1 | 01-01-2005 | 50000 | Senior | 1 | 1 | Account manager, blue chip company 2 | 01-01-2005 | 120000 | CFO | 1 | 1 | CFO of big four bank 3 | 01-03-2005 | 45000 | Jr | 1 | 2 | Entry level Database position. Great start!! 4 | 05-03-2005 | 20000 | Reception | 2 | 3 | Basic office admin, phones and coffee making 5 | 07-02-2005 | 38000 | Graduate | 3 | 1 | Great start for a fresh graduate 6 | 25-06-2005 | 85000 | Team Member | 4 | 4 | Help rebuild peoples lives in Iraq 7 | 25-06-2005 | 45000 | Team Member | 5 | 4 | Anti-Terror proofing parliment house 8 | 25-06-2005 | 60000 | 2IC | 2 | 2 | Second in command of well run NZ IT company 9 | 25-06-2005 | 75000 | Logistics | 4 | 3 | Team player with excellent organisation skills
locid | loccity | loccountry-------+------------+------------- 1 | Sydney | Australia 2 | Wellington | New Zealand 3 | New York | USA 4 | Baghdad | Iraq 5 | Canberra | Australia
The Natural Join (2)
• Final Table (joining Table Job with Table Location
SELECT * FROM Carnie_MyCareer_Job, Carnie_MyCareer_Location WHERE Carnie_MyCareer_Job.locid = Carnie_MyCareer_Location.locid;
Common Column
locid | jobid | jobpostdate | jobsalary | jobposition | secid | jobdesc | loccity | loccountry-------+-------+-------------+-----------+-------------+-------+-------------------------------------+------------+------------- 1 | 1 | 01-01-2005 | 50000 | Senior | 1 | Account manager, blue chip company | Sydney | Australia 1 | 2 | 01-01-2005 | 120000 | CFO | 1 | CFO of big four bank | Sydney | Australia 1 | 3 | 01-03-2005 | 45000 | Jr | 2 | Entry level Database position. Great| Sydney | Australia 2 | 4 | 05-03-2005 | 20000 | Reception | 3 | Basic office admin, phones | Wellington | New Zealand 3 | 5 | 07-02-2005 | 38000 | Graduate | 1 | Great start for a fresh graduate | New York | USA 4 | 6 | 25-06-2005 | 85000 | Team Member | 4 | Help rebuild peoples lives in Iraq | Baghdad | Iraq 5 | 7 | 25-06-2005 | 45000 | Team Member | 4 | Anti-Terror proofing parliment house| Canberra | Australia 2 | 8 | 25-06-2005 | 60000 | 2IC | 2 | Second command of well run company | Wellington | New Zealand 4 | 9 | 25-06-2005 | 75000 | Logistics | 3 | Team player with excellent skills | Baghdad | Iraq
Entities & Relationships
One-to-Many Relationship 1:m
• One to many relationship (1:m) occurs when one record in a table is related to multiple records in another table.
• Example: a job seeking candidate can have many job applications.
• Hence, a candidate table has a 1 to many relationship with the application table.
One-to-Many Relationship 1:m• Example (con’t)
• Entity Relation Diagram:
CanIDCanFirstNameCanLastNameCanSexCanBirthYear
Candidate
JobID*CanID*AppID
Application
1 m
One-to-Many Relationship 1:m• Example (con’t)
• Tables:
canid | canfirstname | canlastname | cansex | canbirthyear
-------+--------------+-------------+--------+--------------
1 | Chris | Carnie | M | 08-01-1981
2 | David | Saddington | M | 21-06-1980
3 | Katie | Lenehan | F | 04-04-1978
4 | Sussie | Kelly | F | 24-11-1969
5 | Ron | Howard | M | 01-01-2000
Candidate (carnie_mycareer_candidate)
canid | appid | jobid-------+-------+------- 1 | 1 | 1 1 | 6 | 5 1 | 12 | 9 2 | 5 | 3 2 | 7 | 5 2 | 10 | 8 3 | 3 | 1 3 | 8 | 5 3 | 11 | 8 3 | 13 | 9 4 | 2 | 1 4 | 4 | 2 4 | 9 | 5
Applicartion (carnie_mycareer_application)
1 m(3)
Many-to-Many Relationship m:m• Many to many relationship (1:m) occurs when one
record in a table a is related to multiple records in another table b; at the same time one record in table b is related to many tables in table a.
• Example: One candidate applies for many jobs; at the same time each of the jobs that candidate has applied for has many other candidates applying for it as well.
• Hence, a candidate table has a many to many (indirect) relationship with the job table.
Many-to-Many Relationship m:m• Example (con’t)
• Entity Relation Diagram:
CanIDCanFirstNameCanLastNameCanSexCanBirthYear
Candidate
JobID*CanID*AppID
Application
1 m
JobIDJobPostDateJobSalaryJobPositionLocID*SecID*Job Desc
Job
1m
Associative Entity
m:m• Many-to-many relationships in the second normal form and
onwards have associative entities (such as application) to preserve the relationship between two entities while preventing the replication of data.
Many-to-Many Relationship m:m• Example (con’t)
• Tables:
jobid | jobpostdate | jobsalary | jobposition | locid | secid-------+-------------+-----------+-------------+-------+------- 1 | 01-01-2005 | 50000 | Senior | 1 | 1 2 | 01-01-2005 | 120000 | CFO | 1 | 1 3 | 01-03-2005 | 45000 | Jr | 1 | 2 4 | 05-03-2005 | 20000 | Reception | 2 | 3 5 | 07-02-2005 | 38000 | Graduate | 3 | 1 6 | 25-06-2005 | 85000 | Team Member | 4 | 4 7 | 25-06-2005 | 45000 | Team Member | 5 | 4 8 | 25-06-2005 | 60000 | 2IC | 2 | 2 9 | 25-06-2005 | 75000 | Logistics | 4 | 3
canid | canfirstname | canlastname | cansex | canbirthyear
-------+--------------+-------------+--------+--------------
1 | Chris | Carnie | M | 08-01-1981
2 | David | Saddington | M | 21-06-1980
3 | Katie | Lenehan | F | 04-04-1978
4 | Sussie | Kelly | F | 24-11-1969
5 | Ron | Howard | M | 01-01-2000
canid | appid | jobid-------+-------+------- 1 | 1 | 1 1 | 6 | 5 1 | 12 | 9 2 | 5 | 3 2 | 7 | 5 2 | 10 | 8 3 | 3 | 1 3 | 8 | 5 3 | 11 | 8 3 | 13 | 9 4 | 2 | 1 4 | 4 | 2 4 | 9 | 5
Candidate (carnie_mycareer_candidate)
Applicartion (carnie_mycareer_application)
Job (carnie_mycareer_job)
1
m(3)
1
m(2)
One candidate has many applications
Each application is for one job
One job has many applications
Each application is for one candidate
Group by, Sub-queries & Complex Joins
Group by• The group by clause allows the records in a table
to be cascaded into groups where their fields in a certain column are equal.
• Example: If you wanted to view the number of applications for each position, you would select all the columns of the application table, grouped by the job ID.
Group by• Example (con’t)
• Code & Tables:
jobid | appid | canid-------+-------+------- 1 | 1 | 1 1 | 2 | 4 1 | 3 | 3 2 | 4 | 4 3 | 5 | 2 5 | 6 | 1 5 | 7 | 2 5 | 8 | 3 5 | 9 | 4 8 | 10 | 2 8 | 11 | 3 9 | 12 | 1 9 | 13 | 3
Applicartion (carnie_mycareer_application)
SELECT jobid, count(appid) FROM carnie_mycareer_application GROUP BY jobid;
• Without group by, the database would not know how to view the count for each jobid.
jobid | count-------+------- 1 | 3 2 | 1 3 | 1 5 | 4 8 | 2 9 | 2
Query Result
Having• Adding the having clause to a group by allows the
user to add an aggregate condition that works similarly to the where clause.
• Example: If you wanted to view the number of applications for positions with more than one applicant then you would add the having after the group by statement.
Group by• Example (con’t)
• Code & Tables:
jobid | appid | canid-------+-------+------- 1 | 1 | 1 1 | 2 | 4 1 | 3 | 3 2 | 4 | 4 3 | 5 | 2 5 | 6 | 1 5 | 7 | 2 5 | 8 | 3 5 | 9 | 4 8 | 10 | 2 8 | 11 | 3 9 | 12 | 1 9 | 13 | 3
Applicartion (carnie_mycareer_application)
SELECT jobid, count(appid) FROM carnie_mycareer_application GROUP BY jobid HAVING count(jobid)count(jobid) > 1;
• the having statement eliminates any jobs with one or less applicants ( i.e. > 1).
Query Result
jobid | count-------+------- 1 | 3 5 | 4 8 | 2 9 | 2
Subqueries• List the Job position and Salary of all Jobs with a salary above the average.
jobsalary | jobposition-----------+------------- 120000 | CFO 85000 | Team Member 60000 | 2IC 75000 | Logistics
avg-------------------- 59777.777777777778
SELECT jobsalary,jobposition FROM carnie_mycareer_job
WHERE jobsalary >
(SELECT AVG(jobsalary) FROM carnie_mycareer_job);
Using subqueries to find the maximum (or minimum)• List the jobposition and job description of the lowest paid job (the job with the minimum salary)
min------- 20000
SELECT jobposition, jobdescFROM carnie_mycareer_jobWHERE jobsalary <= ( SELECT min(jobsalary) FROM carnie_mycareer_job);
jobposition | jobdesc-------------+---------------------------------------------- Reception | Basic office admin, phones and coffee making
Using subqueries to find the maximum (or minimum) “ALL”• List all the job positions and their job descriptions which have salary less or equal to ALL the salary.
jobposition | jobdesc-------------+---------------------------------------------- Reception | Basic office admin, phones and coffee making
jobsalary----------- 50000 120000 45000 20000 38000 85000 45000 60000 75000
SELECT jobposition, jobdescFROM carnie_mycareer_jobWHERE jobsalary <= ALL( SELECT jobsalary FROM carnie_mycareer_job);
ANY operator
SELECT jobposition,jobsalary FROM carnie_mycareer_job WHERE locid != 1 AND jobsalary = ANY
(SELECT jobsalary FROM carnie_mycareer_job WHERE locid =1);
• This query lists all the positions and salaries of jobs not in Sydney where the salary is equal to any of the jobs that are in Sydney
jobposition | jobsalary-------------+----------- Team Member | 45000
jobsalary----------- 50000 120000 45000
In: an Alternate to ANY
jobposition | jobsalary-------------+----------- Team Member | 45000
jobsalary----------- 50000 120000 45000
SELECT jobposition,jobsalary FROM carnie_mycareer_job WHERE locid != 1 and jobsalary IN
(SELECT jobsalary FROM carnie_mycareer_job WHERE locid =1);
• This query lists all the positions and salaries of jobs not in Sydney where the salary is equal to any of the jobs that are in Sydney
Left Outer Join
SELECT * FROM carnie_mycareer_candidate LEFT JOIN carnie_mycareer_application USING (CanID);
canid | canfirstname | canlastname | cansex | canbirthyear | appid | jobid-------+--------------+-------------+--------+--------------+-------+------- 1 | Chris | Carnie | M | 08-01-1981 | 1 | 1 1 | Chris | Carnie | M | 08-01-1981 | 6 | 5 1 | Chris | Carnie | M | 08-01-1981 | 12 | 9 2 | David | Saddington | M | 21-06-1980 | 5 | 3 2 | David | Saddington | M | 21-06-1980 | 7 | 5 2 | David | Saddington | M | 21-06-1980 | 10 | 8 3 | Katie | Lenehan | F | 04-04-1978 | 3 | 1 3 | Katie | Lenehan | F | 04-04-1978 | 8 | 5 3 | Katie | Lenehan | F | 04-04-1978 | 11 | 8 3 | Katie | Lenehan | F | 04-04-1978 | 13 | 9 4 | Sussie | Kelly | F | 24-11-1969 | 2 | 1 4 | Sussie | Kelly | F | 24-11-1969 | 4 | 2 4 | Sussie | Kelly | F | 24-11-1969 | 9 | 5 5 | Ron | Howard | M | 01-01-2000 | |
appid | jobid | canid-------+-------+------- 1 | 1 | 1 2 | 1 | 4 3 | 1 | 3 4 | 2 | 4 5 | 3 | 2 6 | 5 | 1 7 | 5 | 2 8 | 5 | 3 9 | 5 | 4 10 | 8 | 2 11 | 8 | 3 12 | 9 | 1 13 | 9 | 3
canid | canfirstname | canlastname | cansex | canbirthyear-------+--------------+-------------+--------+-------------- 1 | Chris | Carnie | M | 08-01-1981 2 | David | Saddington | M | 21-06-1980 3 | Katie | Lenehan | F | 04-04-1978 4 | Sussie | Kelly | F | 24-11-1969 5 | Ron | Howard | M | 01-01-2000
Right Outer Join
SELECT * FROM carnie_mycareer_candidate RIGHT JOIN carnie_mycareer_application USING (CanID); canid | canfirstname | canlastname | cansex | canbirthyear | appid | jobid-------+--------------+-------------+--------+--------------+-------+------- 1 | Chris | Carnie | M | 08-01-1981 | 1 | 1 4 | Sussie | Kelly | F | 24-11-1969 | 2 | 1 3 | Katie | Lenehan | F | 04-04-1978 | 3 | 1 4 | Sussie | Kelly | F | 24-11-1969 | 4 | 2 2 | David | Saddington | M | 21-06-1980 | 5 | 3 1 | Chris | Carnie | M | 08-01-1981 | 6 | 5 2 | David | Saddington | M | 21-06-1980 | 7 | 5 3 | Katie | Lenehan | F | 04-04-1978 | 8 | 5 4 | Sussie | Kelly | F | 24-11-1969 | 9 | 5 2 | David | Saddington | M | 21-06-1980 | 10 | 8 3 | Katie | Lenehan | F | 04-04-1978 | 11 | 8 1 | Chris | Carnie | M | 08-01-1981 | 12 | 9 3 | Katie | Lenehan | F | 04-04-1978 | 13 | 9
canid | canfirstname | canlastname | cansex | canbirthyear-------+--------------+-------------+--------+-------------- 1 | Chris | Carnie | M | 08-01-1981 2 | David | Saddington | M | 21-06-1980 3 | Katie | Lenehan | F | 04-04-1978 4 | Sussie | Kelly | F | 24-11-1969 5 | Ron | Howard | M | 01-01-2000
appid | jobid | canid-------+-------+------- 1 | 1 | 1 2 | 1 | 4 3 | 1 | 3 4 | 2 | 4 5 | 3 | 2 6 | 5 | 1 7 | 5 | 2 8 | 5 | 3 9 | 5 | 4 10 | 8 | 2 11 | 8 | 3 12 | 9 | 1 13 | 9 | 3
Self Join• Show jobs posted on same day as the job
position 'Logistics‘
jobid | jobpostdate | jobposition-------+-------------+------------- 6 | 25-06-2005 | Team Member 7 | 25-06-2005 | Team Member 8 | 25-06-2005 | 2IC
SELECT job1.JobID, job1.JobPostDate, job1.JobPositionFROM Carnie_MyCareer_Job job1, Carnie_MyCareer_Job job2WHERE job1.JobPostDate = job2.JobPostDateAND job2.JobPosition = 'Logistics'AND job1.JobPosition <> 'Logistics';
Data Integrity with SQL
Data Integrity
locid | loccity | loccountry-------+------------+------------- 1 | Sydney | Australia 2 | Wellington | New Zealand 3 | New York | USA 4 | Baghdad | Iraq 5 | Canberra | Australia
jobid | jobpostdate | jobsalary | jobposition | locid | secid | jobdesc-------+-------------+-----------+-------------+-------+-------+--------------------------------------- 1 | 01-01-2005 | 50000 | Senior | 1 | 1 | Account manager, blue chip company 2 | 01-01-2005 | 120000 | CFO | 1 | 1 | CFO of big four bank 3 | 01-03-2005 | 45000 | Jr | 1 | 2 | Entry level Database position. 4 | 05-03-2005 | 20000 | Reception | 2 | 3 | Basic office admin, phone 5 | 07-02-2005 | 38000 | Graduate | 3 | 1 | Great start for a fresh graduate 6 | 25-06-2005 | 85000 | Team Member | 4 | 4 | Help rebuild peoples lives in Iraq 7 | 25-06-2005 | 45000 | Team Member | 5 | 4 | Anti-Terror proofing parliment 8 | 25-06-2005 | 60000 | 2IC | 2 | 2 | Second in command of well run company 9 | 25-06-2005 | 75000 | Logistics | 4 | 3 | Team player with excellent skills
Primary Key
Foreign Key
Creating the linked foreign keyCREATE TABLE CARNIE_MYCAREER_JOB( JobID JobPostDate JobSalary JobPosition LocID SecID JobDesc CONSTRAINT PKJobID PRIMARY KEY (JobID), CONSTRAINT FKLocID FOREIGN KEY (LocID) REFERENCES
Carnie_Mycareer_Location ON DELETE RESTRICT);
CREATE TABLE CARNIE_MYCAREER_LOCATION( LocID LocCity LocCountry CONSTRAINT PKLocID PRIMARY KEY (LocID));
Check Constraints ExampleCREATE TABLE CARNIE_MYCAREER_APPLICATION( AppID INTEGER NOT NULL, JobID INTEGER NOT NULL, CanID INTEGER NOT NULL,CONSTRAINT PKAppID PRIMARY KEY (AppID, JobID, CanID)CONSTRAINT ValidAppID CHECK (AppID > 0)CONSTRAINT ValidJobID CHECK (JobID > 0)CONSTRAINT ValidCanID CHECK (CanID > 0));CREATE TABLE CARNIE_MYCAREER_CANDIDATE( CanID INTEGER NOT NULL, CanFirstName VARCHAR NOT NULL, CanLastName VARCHAR NOT NULL, CanSex CHAR (1) CHECK (CanSex IN
('M','F')), CanBirthYear VARCHAR NOT NULL, CONSTRAINT PKCanID PRIMARY KEY (CanID));
SQL Syntax for ActionsCREATE TABLE CARNIE_MYCAREER_APPLICATION( AppID INTEGER NOT NULL, JobID INTEGER NOT NULL, CanID INTEGER NOT NULL,CONSTRAINT PKAppID PRIMARY KEY (AppID, JobID, CanID)CONSTRAINT FKJobID FOREIGN KEY (JobID) references
CARNIE_MYCAREER_JOB ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT FKCanID FOREIGN KEY (CanID) references CARNIE_MYCAREER_CANDIDATE ON DELETE CASCADE ON UPDATE CASCADE );
SQL Syntax for Actions• For example trying to delete CanID = 1
from the Candidate table:
DELETE FROM carnie_mycareer_candidate WHERE CanID = 1;
Results in:DELETE 1 (A successful deletion)
The delete action has cascaded to the Application table as observed by doing the following:SELECT * FROM carnie_mycareer_application;
appid | jobid | canid-------+-------+------- 2 | 1 | 4 3 | 1 | 3 4 | 2 | 4 5 | 3 | 2 7 | 5 | 2 8 | 5 | 3 9 | 5 | 4 10 | 8 | 2 11 | 8 | 3 13 | 9 | 3
No CanID = 1 !!!
SQL Syntax for Actions (2)CREATE TABLE CARNIE_MYCAREER_JOB( JobID INTEGER NOT NULL, JobPostDate VARCHAR NOT NULL, JobSalary INTEGER NOT NULL, JobPosition VARCHAR NOT NULL, LocID INTEGER NOT NULL, SecID INTEGER NOT NULL, JobDesc VARCHAR NOT NULL,
CONSTRAINT PKJobID PRIMARY KEY (JobID), CONSTRAINT FKLocID FOREIGN KEY (LocID) REFERENCES
Carnie_Mycareer_Location ON DELETE RESTRICT ON UPDATE CASCADE,
CONSTRAINT FKSecID FOREIGN KEY (SecID) REFERENCES Carnie_Mycareer_Sector
ON DELETE RESTRICT ON UPDATE CASCADE );
SQL Syntax for Actions (2)• For example trying to delete a LocID
from the Location table:DELETE FROM carnie_mycareer_location WHERE LocID = 1;
Will produce the error:update or delete on "carnie_mycareer_location" violates foreign key constraint "fklocid" on "carnie_mycareer_job“
As the foreign key LocID in the Job table restricts the data sharing this key’s value (1) from being deleted in the Job table.
Normalization
1st Normal Form
SectorID JobID JobPosition SecTitle LocCity
1 1 Reception IT Sydney
1 2 Senior IT Melbourne
2 3 CFO Finance Sydney
2 4 Logistics Finance Melbourne
Composite Primary Key
SectorID SectorTitleJobID JobPosition, LocCity
•DATA REDUNDANCY!•Solution : Split into 2 or more tables
• … see the next slide Composite Primary Key
Improving on 1st Normal Form
JobID JobPosition LocCity
1 Reception Sydney
2 Senior Melbourne
3 CFO Sydney
4 Logistics Melbourne
SectorID SecTitle
1 IT
1 IT
2 Finance
2 Finance
The respective primary keys for each table
• Fixes the problem shown in the previous slide
Problem with 2nd Normal Form
CanID CanName CanSuburb CanPostCode
1 Peter Ebeid XXX 111
2 Dane Harris XXX 111
3 Stephanie Ho YYY 222
4 Chris Zaharia YYY 222
Primary Key
CanSuburb CanPostCode
• MORE DATA REDUNDANCY!• Solution: Split into 2 or more tables
• … see the next slide
• Imagine if we had a “candidate” table like this …
Improving on 2nd Normal Form
CanSuburb CanPostCode
XXX 111
YYY 222
The respective primary key for each table
CanID CanName CanSuburb
1 Peter Ebeid XXX
2 Dane Harris XXX
3 Stephanie Ho YYY
4 Chris Zaharia YYY
• Fixes the problem shown in the previous slide
Problem with 3rd Normal Form
CanID CanName CanTaxFileNo
1 Peter Ebeid 111111
2 Dane Harris 222222
3 Stephanie Ho 333333
4 Chris Zaharia 444444
Primary Key
CanID CanTaxFileNo andCanTaxFileNo CanID
• MORE DATA REDUNDANCY!• Solution: Split into 2 or more tables
• … see the next slide
• Imagine if we had a “candidate” table like this …
Or instead of tax file number, maybe email address, ormobile no.
Improving on 3rd Normal Form
The respective primary key for each table
CanID CanName
1 Peter Ebeid
2 Dane Harris
3 Stephanie Ho
4 Chris Zaharia
• Fixes the problem shown in the previous slide• It’s Boyce Codd Normal Form (BCNF)
CanID CanTaxFileNo
1 111111
2 222222
3 333333
4 444444
An Example of Creating a View
CREATE VIEW joblocation(jobID, position, salary, locID, City, Country)AS SELECT jobID, jobposition, jobsalary, locid, locCity, locCountry
FROM Carnie_MyCareer_Job natural join Carnie_MyCareer_Location;
An Example of Creating a View
position | city-------------+---------- Team Member | Canberra
• Query exactly as if a table
SELECT position, city FROM joblocation WHERE city = 'Canberra';
Thank You
