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

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Presentation on theme: "Concepts of Database Management Seventh Edition Chapter 3 The Relational Model 2: SQL."— Presentation transcript:

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 2

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

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 11

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 12

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

14 Non-Graded Exercise 14 1.Show all the fields and records from Rep table 2.Show all fields and records Part table 3.Show the Last name and First name of all Sales Rep from Rep table 4.Show the Part number, Description, On Hand Quantity and Price from Part table

15 Simple Retrieval – Filtering Records 15 Filtering records to retrieve using WHERE clause –Syntax: SELECT * FROM –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 16

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

18 Relational Operators 18 OperatorDescriptionExample >Greater ThanAge>20 =Greater than or EqualCreditLimit >= <=Less than or EqualBalance<=5000 <>Not EqualCity <> Grove DatabaseExample MS AccessOrderDate = #10/21/2013# MySQLOrderDate = DATE( ) Date Comparisons

19 Non-Graded Exercise 19 1.Show all Customers that comes from the City of Altonville from Customer table 2.Show all products from Part table whose class is AP 3.Show all Customers whose Balance is greater than 7000 from Customer table 4.Show all Customers whose Credit Limit is above or equal to 7500 from Customer table 5.Show all Customers whose balance is less than 500 from Customer table 6.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 20

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

22 AND – Truth Table (Example) Example : Age>20 AND State=Pohnpei 22 AgeStateResult/Answer 20ChuukFalse 21YapFalse 19PohnpeiFalse 21PohnpeiTrue

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

24 OR – Truth Table (Example) Example : Age>20 OR State=Pohnpei 24 AgeStateResult/Answer 20ChuukFalse 21YapTrue 19PohnpeiTrue 21PohnpeiTrue

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

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

27 Non-Graded Exercise 27 1.Show all products from Part table whose class is AP and its price is above $400 2.Show all Customers that comes from either the City of Fillmore or Grove from Customer table 3.Show all Customers whose Credit Limit is $7,500 but its Balance is above $5,000 from Customer table 4.Show all products whose warehouse is from either 1 or 2 5.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 28

29 Compound Conditions (continued) 29 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 –Example 2: SELECT * FROM Orders WHERE Orderdate BETWEEN #10/20/2013# AND #10/21/2013

30 Non-Graded Exercise 30 1.Show all products from Part whose Class is not from AP 2.Show all products from Part whose Warehouse is not from Warehouse number 3 3.Show all customers from Customer whose sales representative is not Repnum no Show all products from Part whose Price is from $300 to $ 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 (/) 31

32 Computed Fields (continued) 32 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 3-26: Query results FIGURE 3-25: SQL query with a computed field and condition 33

34 Non-Graded Exercise 34 1.Show customer name and a computed field name Net using the formula CreditLimit – Balance from Customer table. 2.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. 3.Get the Running Total per product from Part table by multiplying Quantity on Hand by price. Show also the Description of the product. 4.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 35

36 Using LIKE operator and wildcards 36 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 37 –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 38 1.Show all products from Part table that starts with letter D 2.Show all customers from Customer table whose Street starts with 28 3.Using IN show products whose class is AP or SG from Part table 4.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 39

40 Using the ORDER BY statement 40 –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 41 1.Show all products from Part table and sort it according to Product name 2.Show all products from Part table and sort it according to Warehouse and then product name 3.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 42

43 Using Aggregate Functions (COUNT, SUM, AVG, MAX, MIN) 43 –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 SELECT SUM(Balance) as TotalBalance FROM Customer WHERE CreditLimit=5000

44 Non-Graded Exercise 44 1.Count all the products from Part table 2.Count all the products from Part table whose Class is either AP or SG 3.Give the Total for the Quantity On Hand from Part table 4.Give the Sum or Total for the Quoted Price from Orderline table 5.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 45

46 Using Subquery 46 –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 47

48 Using GROUP BY 48 –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 49 –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 50 1.Using subquery show orders from Orderline table that has a class of AP in Part table 2.Count all customers from Customer table per City. 3.Sum all Quantity on Hand from Part table per Warehouse Number. 4.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: 1.SELECT clause: list all fields you want to display 2.FROM clause: list all tables involved in the query 3.WHERE clause: give the condition that will restrict the data to be retrieved to only those rows from the two tables that match 4.Or you could use INNER JOIN in same manner as no. 3 51

52 Joining tables example 52 –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 53 1.Using WHERE clause join Orderline and Part tables showing Ordernum from Orderline table then Partnum and Description from Part table 2.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 54

55 Updating Table using UPDATE command 55 –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 56 1.Using update command from Customer table restore back the City of Customer name Klines from Manila to Fillmore 2.Using update command from Rep table restore back the Firstname and Lastname of Sales Rep John Doe to Juan Perez 3.Using update command restore back from Part table to OnHand quantity plus 1 this time whose Warehouse is 2 4.Using update command from Part change the Class name to HH whose class name is HW 5.Using update Change all the City of Rep table to Ponpei and Rate to 0.08

57 Updating Table using INSERT command 57 –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 58

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

60 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 61

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 62

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 63

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 64

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 65


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