1. Concepts of Database Management Seventh Edition
Chapter 3
The Relational Model 2: SQL

2. Objectives Introduce Structured Query Language (SQL)
Use simple and compound conditions in SQL
Use computed fields in SQL
Use built-in SQL functions
Use subqueries in SQL

3. Objectives (continued)
Group records in SQL
Join tables using SQL
Perform union operations in SQL
Use SQL to update database data
Use an SQL query to create a table in a database

4. Introduction SQL (Structured Query Language)
Allows users to query a relational database
Must enter commands to obtain the desired results
Standard language for relational database manipulation

5. Getting Started with SQL
If you are completing the work in this chapter using Microsoft Office Access 2007, Microsoft Office Access 2010, or MySQL version 4.1 or higher, the following sections contain specific information about your DBMS

6. Getting Started with Microsoft Office Access 2007 and 2010
If you are using the Access 2007 or 2010 version of the Premiere Products database provided with the Data Files for this text:
Tables in the database have already been created
You will not need to execute the CREATE TABLE commands to create the tables or the INSERT commands to add records to the tables

7. Getting Started with Microsoft Office Access 2007 and 2010 (continued)
To execute SQL commands shown in the figures in Access 2007 or Access 2010:
Open the Premiere Products database
Click the Create tab on the Ribbon
Click the Query Design button in the Other group
Click the Close button in the Show Table dialog box
Click the View button arrow in the Results group on the Query Design Tools tab, then click SQL View
The Query1 tab displays the query in SQL view, ready for you to type your SQL commands

8. Getting Started with MySQL
MySQL-Premiere script provided with the Data Files for this text will:
Activate the database
Create the tables
Insert the records
To run a script in MySQL:
Type the SOURCE command followed by the name of the file
Press the Enter key

9. Getting Started with MySQL (continued)
Before typing commands in MySQL, you must activate the database by typing the USE command followed by the name of the database
The most recent command entered in MySQL is stored in a special area of memory called the statement history

10. Table Creation SQL CREATE TABLE command
Creates a table by describing its layout
Typical restrictions placed on table and column names by DBMS
Names cannot exceed 18 characters
Names must start with a letter
Names can contain only letters, numbers, and underscores (_)
Names cannot contain spaces

11. Table Creation (continued)
INTEGER
Number without a decimal point
SMALLINT
Uses less space than INTEGER
DECIMAL(p,q)
P number of digits; q number of decimal places
CHAR(n)
Character string n places long
DATE
Dates in DD-MON-YYYY or MM/DD/YYYY form

12. Simple Retrieval SELECT-FROM-WHERE: SQL retrieval command
SELECT clause: lists fields to display
FROM clause: lists table or tables that contain data to display in query results
WHERE clause (optional): lists any conditions to be applied to the data to retrieve
Simple condition: field name, a comparison operator, and either another field name or a value

13. Simple Retrieval (continued)
Retrieving all fields and all records
Syntax: SELECT * FROM <table>
Example 1: SELECT * FROM Customer
Example 2: SELECT * FROM Rep
Retrieving specific field(s)
Syntax: SELECT <field1>, <field2>,..<fieldn> FROM <table>
Example 1: SELECT Customername, City, State FROM Customer
Example 2: SELECT Repnum, Lastname, Firstname, Commission, Rate FROM Rep

14. Non-Graded Exercise Show all the fields and records from Rep table
Show all fields and records Part table
Show the Last name and First name of all Sales Rep from Rep table
Show the Part number, Description, On Hand Quantity and Price from Part table

15. Simple Retrieval – Filtering Records
Filtering records to retrieve using WHERE clause
Syntax: SELECT * FROM <table>
Example 1: (Filtering records with a Text/String field)
SELECT * FROM Customer WHERE City=‘Grove’
Example 2: (Filtering records with a Numeric field)
SELECT * FROM Customer WHERE CreditLimit=7500
Example 3: (Filtering records using specific fields)
SELECT Customername, City WHERE City = ‘Grove’
Example 4: (Filtering records using not equal)
SELECT * FROM City WHERE City <> ‘Fillmore’
Note : If it is a string or a text the value should have a quote like in ‘Grove’ but if it is numeric do not put a quote.

16. Simple Retrieval (continued)
FIGURE 3-6: SQL query with WHERE condition

17. Simple Retrieval (continued)
FIGURE 3-7: Query results

18. Relational Operators Date Comparisons Operator Description Example
>
Greater Than
Age>20
<
Less than
Age<21 =
Equal
City=‘Grove’
>=
Greater than or Equal
CreditLimit >= 10000
<=
Less than or Equal
Balance<=5000
<>
Not Equal
City <> ‘Grove’
Date Comparisons
Database
Example
MS Access
OrderDate = #10/21/2013#
MySQL
OrderDate = DATE(‘ ’)

19. Non-Graded Exercise
Show all Customers that comes from the City of Altonville from Customer table
Show all products from Part table whose class is AP
Show all Customers whose Balance is greater than 7000 from Customer table
Show all Customers whose Credit Limit is above or equal to 7500 from Customer table
Show all Customers whose balance is less than 500 from Customer table
Show all orders from Orders table whose order is beyond 10/20/2013

20. Compound Conditions Compound condition
Connecting two or more simple conditions using one or both of the following operators: AND and OR
Preceding a single condition with the NOT operator
Connecting simple conditions using AND operator
All of the simple conditions must be true for the compound condition to be true
Connecting simple conditions using OR operator
Any of the simple conditions must be true for the compound condition to be true

21. AND – Truth Table
In order for AND to be true all conditions/expressions should be true
Condition 1
Condition 2
Result
False
True

22. AND – Truth Table (Example)
Example : Age>20 AND State=‘Pohnpei’
Age
State
Result/Answer 20
Chuuk
False 21
Yap 19
Pohnpei
True

23. OR – Truth Table
In order for OR to be True at least one conditions/expressions should be true
Condition 1
Condition 2
Result
False
True

24. OR – Truth Table (Example)
Example : Age>20 OR State=‘Pohnpei’
Age
State
Result/Answer 20
Chuuk
False 21
Yap
True 19
Pohnpei

25. Compound Conditions (continued)
FIGURE 3-15: Compound condition that uses the AND operator
FIGURE 3-16: Query results

26. Compound Conditions (continued)
FIGURE 3-17: Compound condition that uses the OR operator
FIGURE 3-18: Query results

27. Non-Graded Exercise
Show all products from Part table whose class is AP and its price is above $400
Show all Customers that comes from either the City of Fillmore or Grove from Customer table
Show all Customers whose Credit Limit is $7,500 but its Balance is above $5,000 from Customer table
Show all products whose warehouse is from either 1 or 2
Show all products whose On hand quantity is above 20 and coming from Warehouse no. 3

28. Compound Conditions (continued)
Preceding a condition by NOT operator
Reverses the truth or falsity of the original condition
BETWEEN operator
Value must be between the listed numbers

29. Compound Conditions (continued)
Using NOT operator
Example 1: SELECT * FROM Customer WHERE NOT City=‘Grove’
Example 2: SELECT * FROM Customer WHERE NOT CreditLimit=10000
Using BETWEEN operator
Example 1: SELECT * FROM Customer WHERE Balance BETWEEN 5000 AND 10000
Example 2: SELECT * FROM Orders WHERE Orderdate BETWEEN #10/20/2013# AND #10/21/2013

30. Non-Graded Exercise
Show all products from Part whose Class is not from AP
Show all products from Part whose Warehouse is not from Warehouse number 3
Show all customers from Customer whose sales representative is not Repnum no. 65
Show all products from Part whose Price is from $300 to $600.
Show all products from Part whose On hand quantity is from 20 to 50

31. Computed Fields Computed field or calculated field
Field whose values you derive from existing fields
Can involve:
Addition (+)
Subtraction (-)
Multiplication (*)
Division (/)

32. Computed Fields (continued)
Numeric Computed Fields
Example 1: Computing the Net by deducting Credit Limit from Balance
SELECT Customername, (Balance-CreditLimit) as Net FROM Customer
Example 2: Computing the Running Total by Multiplying On hand quantity with Price
SELECT Partnum, Description, OnHand * Price as RunningTotal FROM Part
Non-numeric Computed Field
Example 1: Concatenating or Joining Last name and First name of the Sales as Full Name
SELECT Repnum, Lastname + “, “ + Firstname as Fullname FROM Rep

33. Computed Fields (continued)
FIGURE 3-25: SQL query with a computed field and condition
FIGURE 3-26: Query results

34. Non-Graded Exercise
Show customer name and a computed field name Net using the formula CreditLimit – Balance from Customer table.
Get the Running Total from each order by multiplying Number Ordered and Quoted Price of the Orderline table. Aside from the Running Total show also the Order Number.
Get the Running Total per product from Part table by multiplying Quantity on Hand by price. Show also the Description of the product.
Make a concatenated field for Street, City, State and Zip fields and named it Address, from Customer table. Show also the Customer name before the address.

35. Using Special Operators (LIKE and IN)
Wildcards in Access SQL
Asterisk (*): collection of characters
Question mark (?): any individual character
Wildcards in MySQL
Percent sign (%): any collection of characters
Underscore (_): any individual character
To use a wildcard, include the LIKE operator in the WHERE clause
IN operator provides a concise way of phrasing certain conditions

36. Using LIKE operator and wildcards
Using asterisk for collection of characters pattern
Example 1: Displays customer whose name starts with letter B
SELECT * FROM Customer WHERE customername LIKE ‘B*’
Example 2: Displays customer whose name starts with the word Brook
SELECT * FROM Customer WHERE customername LIKE ‘Brook*’
Using question mark for individual/single character
Example 1: Display orders whose partnum starts with letter K followed by any 3 characters.
SELECT * FROM Orderline WHERE partnum LIKE ‘K???’
Example 2: Display product whose class startswith letter A followed by one character.
SELECT * FROM Part WHERE class LIKE ‘A?’

37. Using the IN operator
Example 1: Displays customer whose credit limit is either $5,000 or $10,000 or $15,000
SELECT * FROM Customer WHERE creditlimit IN(5000,10000,15000)
Example 2: Displays customer who comes from the City of Grove, Crystal, Fillmore or Northfield
SELECT * FROM Customer WHERE city IN(‘Grove’,’Crystal’,’Fillmore’,’Northfield’)

38. Non-Graded Exercise
Show all products from Part table that starts with letter ‘D’
Show all customers from Customer table whose Street starts with 28
Using IN show products whose class is AP or SG from Part table
Using IN show customers whose Credit Limit is either 5000, or

39. Sorting Sort data using the ORDER BY clause
Sort key: field on which to sort data
When sorting data on two fields:
Major sort key (or primary sort key): more important sort key
Minor sort key (or secondary sort key): less important sort key

40. Using the ORDER BY statement
Example 1: Displays customer sorted by customer name
SELECT * FROM Customer ORDER BY customername
Example 2: Displays sales rep sorted by Lastname then Firstname
SELECT * FROM Rep ORDER BY Lastname, Firstname
Example 3: Displays sales rep sorted by Lastname in descending order
SELECT * FROM Rep ORDER BY Lastname DESC
Example 4: Displays customer sorted by City whose Credit Limit is $10,000
SELECT * FROM Customer WHERE CreditLimit = ORDER BY city

41. Non-Graded Exercise
Show all products from Part table and sort it according to Product name
Show all products from Part table and sort it according to Warehouse and then product name
Show all products ordered from Orderline table and sort it according to Number of product ordered and in Descending order

42. Built-in Functions Built-in functions (aggregate functions) in SQL
COUNT: calculates number of entries
SUM or AVG: calculates sum or average of all entries in a given column
MAX or MIN: calculates largest or smallest values respectively

43. Using Aggregate Functions (COUNT, SUM, AVG, MAX, MIN)
Example 1: Count all how many customers in Customer table
SELECT COUNT(*) as CustomerCount FROM Customer
Example 2: Count how many customers from the City of Grove
SELECT COUNT(*) as CountGrove FROM Customer WHERE city = ‘Grove’
Example 3: Sum all Balance from all Customers
SELECT SUM(Balance) as TotalBalance FROM Customer
Example 4: Sum all Balance from all Customers for those who a CreditLimit of $5,000
WHERE CreditLimit=5000

44. Non-Graded Exercise Count all the products from Part table
Count all the products from Part table whose Class is either ‘AP’ or ‘SG’
Give the Total for the Quantity On Hand from Part table
Give the Sum or Total for the Quoted Price from Orderline table
Give the Sum or Total for the Quoted Price from Orderline table whose Quoted Price is above $400

45. Subqueries Subquery: inner query Subquery is evaluated first
Outer query is evaluated after the subquery

46. Using Subquery
Example 1: Select orders where whose parts/products are from Warehouse No. 3
SELECT Ordernum FROM Orderline WHERE Partnum IN (SELECT Partnum FROM Part WHERE Warehouse = ‘3’)

47. Grouping Create groups of records that share a common characteristic
GROUP BY clause indicates grouping in SQL
HAVING clause is to groups what the WHERE clause is to rows

48. Using GROUP BY
Example 1: Count how many customers per Sales Representative
SELECT Repnum, COUNT(*) as TotalCustomersPerRep FROM Customer GROUP BY Repnum
Example 2: Get the Total of how much Quantity on Hand per Class of all the products
SELECT Class, SUM(OnHand) as TotalPerClass
FROM Part GROUP BY Class

49. Using HAVING
Example 2: Get the Total of how much Quantity on Hand per Class of all products that have Quantity on hand above 70
SELECT Class, SUM(OnHand) as TotalPerClass
FROM Part GROUP BY Class HAVING SUM(OnHand) > 70

50. Non-Graded Exercise
Using subquery show orders from Orderline table that has a class of ‘AP’ in Part table
Count all customers from Customer table per City.
Sum all Quantity on Hand from Part table per Warehouse Number.
Display the Sum of Quantity on Hand from Part table per Warehouse Number that has Total Quantity on hand above 100.

51. Joining Tables Queries can locate data from more than one table
Enter appropriate conditions in the WHERE clause
To join tables, construct the SQL command as:
SELECT clause: list all fields you want to display
FROM clause: list all tables involved in the query
WHERE clause: give the condition that will restrict the data to be retrieved to only those rows from the two tables that match
Or you could use INNER JOIN in same manner as no. 3

52. Joining tables example
Example 1: Joining tables using WHERE clause
SELECT CustomerNum, CustomerName, Rep.Repnum, Lastname, Firstname FROM Customer, Rep
WHERE Customer.Repnum = Rep.Repnum
Example 2: Joining tables using INNER JOIN
SELECT A.CustomerNum, A.CustomerName, B.Repnum, B.Lastname, B.Firstname FROM Customer A INNER JOIN Rep B ON A.Repnum = B.Repnum

53. Non-Graded Exercise
Using WHERE clause join Orderline and Part tables showing Ordernum from Orderline table then Partnum and Description from Part table
Using INNER JOIN, join Orderline and Part tables showing Ordernum from Orderline table then Partnum and Description from Part table

54. Updating Tables UPDATE command makes changes to existing data
INSERT command adds new data to a table
DELETE command deletes data from the database

55. Updating Table using UPDATE command
Example 1: Updating one field
UPDATE Customer SET City=‘Manila’ WHERE Customernum=‘524’
Example 2: Updating more than one field
UPDATE Rep SET Lastname=‘Doe’, Firstname=‘John’ WHERE Repnum=‘65’
Example 3: Updating involving computation
UPDATE Part SET OnHand=OnHand-1 WHERE Warehouse=‘2’

56. Non-Graded Exercise
Using update command from Customer table restore back the City of Customer name Kline’s from Manila to Fillmore
Using update command from Rep table restore back the Firstname and Lastname of Sales Rep John Doe to Juan Perez
Using update command restore back from Part table to OnHand quantity plus 1 this time whose Warehouse is ‘2’
Using update command from Part change the Class name to ‘HH’ whose class name is ‘HW’
Using update Change all the City of Rep table to Ponpei and Rate to 0.08

57. Updating Table using INSERT command
Example 1: Inserting a record involving all fields
INSERT INTO Part VALUES ('RC24','Rice Cooker',100,'AP','3',75.50)
Example 2: Inserting a record involving specific fields
INSERT INTO Part (Partnum, Description,Class,Price) VALUES ('PL10','Power Lifts','SG',250.00)

58. Creating a Table from a Query
INTO clause
Saves the results of a query as a table
Specified before FROM and WHERE clauses
MySQL
Create the new table using a CREATE TABLE command
Use an INSERT command to insert the appropriate data into the new table

59. Creating a Table from a Query (continued)
FIGURE 3-60a: Query to create a new table (Access) 59

60. Creating a Table from a Query (continued)
FIGURE 3-60b: Query to create a new table (for Oracle and MySQL) 60

61. Summary of SQL Commands
Generic versions of SQL commands for every example presented in this chapter
In most cases, commands in Access are identical to the generic versions
For those commands that differ, both the generic version and the Access version are included

62. Summary
Structured Query Language (SQL) is a language that is used to manipulate relational databases
Basic form of an SQL query: SELECT-FROM-WHERE
Use CREATE TABLE command to describe table layout to the DBMS, which creates the table
In SQL retrieval commands, fields are listed after SELECT, tables are listed after FROM, and conditions are listed after WHERE
In conditions, character values must be enclosed in single quotation marks

63. Summary (continued)
Compound conditions are formed by combining simple conditions using either or both of the following operators: AND and OR
Sorting is accomplished using ORDER BY clause
When the data is sorted in more than one field, can have a major and minor sort key
Grouping: use the GROUP BY clause
HAVING clause: restricts the rows to be displayed

64. Summary (continued)
Joining tables: use a condition that relates matching rows in the tables to be joined
Built-in (aggregate) functions: COUNT, SUM, AVG, MAX, and MIN
One SQL query can be placed inside another; the subquery is evaluated first
UNION operator: unifies the results of two queries

65. Summary (continued)
Calculated fields: include the calculation, the word AS, the name of the calculated field
INSERT command adds a new row to a table
UPDATE command changes existing data
DELETE command deletes records
INTO clause is used in a SELECT command to create a table containing the results of the query