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Sq lite module3


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Module 3 out of 9; SQLite training slides, databases, SQL, ERD, software design, database

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Sq lite module3

  1. 1. MODULE 3: THE RDBMS AND THE RELATIONAL MODEL SQL and Scripting Training (C) 2020-2021 Highervista, LLC 1
  2. 2. 2 TOPICS RDBMS Concept Preview Understanding the RDBMS Model Data Modeling Concepts: Part 1 A Primer to Relational Algebra Recap: Understanding the RDBMS Model Types of Data
  3. 3. 3 VIDEO: RDBMS
  4. 4. UNDERSTANDING THE RDBMS MODEL SQL and Scripting Training
  5. 5. 5 CHARACTERISTICS OF A RELATIONAL TABLE Characteristics of a Relational Table (TutorialsPoint, 2020)
  6. 6. 6 KEYS Consist of one or more attributes that determine other attributes Used to ­ Ensure that each row in a table is uniquely identifiable ­ Establish relationships among tables and ensure data integrity Primary key (PK)—Attribute or combination of attributes that uniquely identifies a row Source: Microsoft Images
  7. 7. 7 RELATIONAL DATABASE KEYS Relational Database Keys (TutorialsPoint, 2020)
  8. 8. 8 EXAMPLE OF A SIMPLE RELATIONAL DATABASE Example of a Simple Relational Database (TutorialsPoint, 2020)
  10. 10. 10 INTEGRITY RULES: AN EXAMPLE Integrity Rules: An Example (TutorialsPoint, 2020)
  11. 11. 11 WAYS TO HANDLE NULLS NOT NULL constraint—Placed on a column to ensure that every row in the table has a value for that column UNIQUE constraint—Restriction placed on a column to ensure that no duplicate values exist for that column Is a field NOT NULL or UNIQUE in your database model? Be sure to indicate this in your Data Dictionary.
  12. 12. DATA MODELING CONCEPTS SQL and Scripting Training
  13. 13. 13 DATA MODELING OBJECTIVES Understand concepts of data modeling and its purpose Learn how relationships between entities are defined and refined, and how they are incorporated into the database design process Learn how ERD components affect database design and implementation Learn how to interpret the modeling symbols
  14. 14. 14 IMPORTANCE OF DATA MODEL Blueprint—official documentation ­ blueprint of house Employees w/o DB knowledge can understand ­ a data model diagram vs. a list of tables ­ an effective communication tool ­ improves interaction among managers, designers, and end users Independence from a particular DBMS ­ network DB, object-oriented DB, etc.
  15. 15. 15 DATA MODEL Model—an abstraction of a real-world object or event ­ useful in understanding complexities of the real-world environment Data model ­ a diagram that displays a set of tables and the relationships between them ­ a foundation ­ next slides: Entity Relationship Diagram (ERD) examples West and Fowler (1999)
  16. 16. 16 ENTITY RELATIONSHIP DIAGRAM (ERD) PROCEDURE Relatively simple representations of complex real-world data structures Data modeling is an iterative process. A "complete" and "100% error free" data model is impossible! An "optimized" data model is possible …
  17. 17. 17 ERD STYLES Active link to diagram Chen ERD Style Notation
  18. 18. 18 ERD STYLES Active link to diagram Crow’s Foot ERD Notation Style
  19. 19. 19 WHAT IS AN ERD? ERD is a data modeling technique used in software engineering to produce a conceptual data model of an information system. ERDs illustrate the logical structure of databases. ERDs represent 'business' or 'use' cases
  21. 21. 21 DATA MODEL—ERD The data modeling revolves around discovering and analyzing organizational and user's data requirements (use cases). Requirements based on policies, meetings, procedures, system specifications, etc. • Identify what data is important • Identify what data should be maintained
  22. 22. 22 DATA MODEL— ERD The major activity of this phase is identifying entities, attributes, and their relationships to construct model using the Entity Relationship Diagram. "Logical" (or design) names include: Entity/Attribute/Relationship "Physical" implementation names include: Table, Column, Line Entity à table Attribute à column Relationship à line
  23. 23. 23 ERD NOTATION Digging into the three components in ERDs ­ Entity ­ Attributes ­ Relationships
  24. 24. 24 ENTITY An Entity is a collection of data, using a rectangle with attributes listed inside the entity ‘box.' For example, an entity STUDENT could include the attributes StudentID, Name, Registered, Region, etc. A second entity following this example would be COURSE, which would include the attributes Title, Credit, Quota.
  26. 26. 26 ENTITY RELATIONSHIP NOTATION Digging into the three components in ERDs ­ Entity ­ Attributes ­ Relationships
  27. 27. 27 ENTITY An entity is a collection of data, using a rectangle with attributes listed inside the entity "box." For example, STUDENT could include the attributes student_id, student_name, student_address, etc. A second entity following this example would be COURSE, which would include the attributes course_name, course_number, etc.
  28. 28. 28 CROW'S FOOT NOTATION FOR ENTITY Entity: ­ Represented by a rectangle, with its name on the top. The name is singular (entity) rather than plural (entities). Entity name can be upper case (ENTITY) or lower case (entity).
  29. 29. 29 HOW TO FIND ENTITIES Entity—a person, place, object, or event about which you can store information (e.g. supplier, machine tool, employee, utility pole, airline seat, etc.). ­ Tangible: CUSTOMER, PRODUCT ­ Intangible: ORDER, ACCOUNTS RECEIVABLE ­ Look for singular nouns (beginner) ­ Some ″standards″ place entity names in UPPER CASE (not required) ­ A proper noun is not a good candidate …
  30. 30. 30 ATTRIBUTES Within the Entity (for example, within the student entity) are attributes describing the student. Crow's foot Chen style
  31. 31. 31 ATTRIBUTES Describe details about an entity Entity: Employee Attributes: ­Employee-Name ­Address (composite) ­Phone Extension ­Date-of-Hire ­Job-Skill-Code ­Salary
  32. 32. 32 ATTRIBUTES • The individual bits of data that make up an entity. • Attributes are listed within the entity. • If an attribute is used to identify the entity, it is the primary key and is underlined or preceded with an *. • If it refers to the identifying attribute of another entity, it is a foreign key and is commonly italicized (not in this model). • If you aren't actually storing an attribute, but calculating it from other attributes, it's a derived attribute, and has a dashed outline.
  33. 33. 33 HOW TO FIND ATTRIBUTES Attributes are ­ Data objects that either identify or describe entities (property of an entity). ­ Descriptors whose values are associated with individual entities of a specific entity type. ­ To identify attributes, find and extract the names that appear to be descriptive noun phrases.
  34. 34. 34 TERMINOLOGY: ENTITY INSTANCE Entity instance—a single occurrence within the entity. ­ This example contains six entity instances. Student ID Last Name First Name 2144 Arnold Betty 3122 Taylor John 3843 Simmons Lisa 9844 Macy Bill 2837 Leath Heather 2293 Wrench Tim Entity: STUDENT instanc e
  35. 35. 35 TYPES OF ENTITIES A weak entity is shown as a double rectangle in a data model, because it doesn't have its own unique key—it only exists in relation to the entity it belongs to. An associative entity (easier to see in the second type of diagram), is shown with a dashed outline and connector. This type of entity is needed wherever you have many-to-many relationships. To create an associative entity in the first style of diagram, add an entity shape and a relationship shape, and group the two shapes together.
  36. 36. 36 PREVIEW: CLASSES OF ATTRIBUTES Simple attribute Composite attribute Primary Key attribute Derived attributes Single-Valued attribute Multi-Valued attribute
  37. 37. 37 SIMPLE/COMPOSITE ATTRIBUTE A simple attribute cannot be subdivided. ­ Examples: age, gender, marital status A composite attribute can be further subdivided to yield additional attributes. ­ Examples: ­ ADDRESS à Street, City, State, Zip ­ PHONE NUMBER à Area code, Exchange
  38. 38. 38 IDENTIFIER (PRIMARY KEY AND COMPOSITE IDENTIFIER) Attributes that uniquely identify entity instances become a Primary Key (PK) in an RDBMS
  39. 39. 39 DERIVED ATTRIBUTE Not physically stored within the database Derived by using an algorithm ­ Example 1: Late Charge of 2% ­ MS Access: InvoiceAmt * 0.02 ­ Example 2: Age can be derived from the date of birth and the current date. ­ MS Access: int(Date() – Emp_Dob)/365)
  40. 40. 40 SINGLE-VALUED ATTRIBUTE Can have only a single (atomic) value. ­ Examples: ­ A person can have only one social security number. ­ A manufactured part can have only one serial number. ­ A single-valued attribute is not necessarily a simple attribute. ­ Part No: CA-08-02-189935 ­ Location: CA, Factory#:08, shift#: 02, part#: 189935
  41. 41. 41 MULTI-VALUED ATTRIBUTES Can have many values. ­Examples: ­ A person may have several college degrees. ­ A household may have several phones with different numbers. ­ A car can be one or more colors.
  42. 42. 42 RELATIONSHIPS Relationships (relationship lines) show how entities are related to each other. Relationships occur between each pair of entities. Relationship lines are bidirectional (operate in both directions). Relationship connectors use Crow's foot notation to show how many of each entity are related to another entity. Example (relationship between student and enrollment) oOne student has one or more enrollments oOne enrollment has only one student
  43. 43. 43 HOW TO FIND RELATIONSHIPS o Relationships are associations between two or more entities. o Typically, a relationship is indicated by a verb connecting two or more entities. o Relationships should be classified in terms of cardinality. §Cardinality: one-to-one, one-to- many, etc.
  44. 44. 44 MORE ABOUT RELATIONSHIP Business rule of a relationship should be bidirectional. ­A student must be enrolled in many curriculums (student to curriculum). ­Each curriculum might be studied by many students (curriculum to student).
  45. 45. 45 CROW'S FOOT—1:1, OPTIONAL RELATIONSHIP (OR) ON ONE SIDE A person might or might not be a programmer, but a programmer must be a person. SUB TYPE ProgrammerPerson 2 Crow's Foot – 1: 1 (McFarland, 2020)
  46. 46. 46 CROW'S FOOT—1:M RELATIONSHIP Each department hires many employees, and each employee is hired by one department. EMPLOYEEDEPARTMT HIRES IS_HIRED_BY Crow's Foot – 1:M (McFarland, 2020)
  47. 47. 47 CROW'S FOOT—1:M WITH OR ON MANY SIDE A person might be or might not be a member, but could be found multiple times (if the member entity represents membership in multiple clubs, for instance). A member must have only a single person. CHILD MEMBERPERSON
  48. 48. 48 CROW'S FOOT: 1:M WITH OR ON BOTH SIDE A person might have no phone, one phone, or lots of phones, and that phone might be unowned or can only be owned by a person. POSSESSION PHONEPERSON 4
  49. 49. 49 CROW'S FOOT—M:N RELATIONSHIP Each student takes many classes, and a class must be taken by many students. Note: Many-to-many relationships cannot be allowed in the data model because they cannot be represented by the relational model. STUDENTCLASS TAKES IS_TAKEN_BY
  50. 50. RECAP: UNDERSTANDING THE RDBMS MODEL SQL and Scripting Training
  51. 51. 51 REVIEW: KEY TERMS IN THE RELATIONAL MODEL What is a Database? How is a Database different from a Database Management System? What is a Schema? What is Metadata?
  52. 52. 52 TERMINOLOGY OF THE RDBMS Logical Name Physical Implementation Name Tuple Row (or record) Attribute Field (or column) Entity Table
  54. 54. 54 REVIEW: DATABASE—TABLES—RECORDS Database, Tables and Records (TutorialsPoint, 2020)
  55. 55. 55 REVIEW: PRIMARY KEY AND FOREIGN KEY Primary key (PK)—A unique identifier for a record. Each PK must be unique. Foreign key (FK)—A field within a table that is a PK in another table.
  56. 56. 56 DATABASE SCHEMA OR ENTITY RELATIONSHIP DIAGRAM (ERD) An Entity Relationship Diagram (ERD) serves as a 'blueprint' for the database. An ERD is also known as a Database Schema.
  57. 57. 57 DATABASE SCHEMA OR ENTITY RELATIONSHIP DIAGRAM (ERD) What is the Primary Key for lab_orders, patient_info, primary_care_doctors, and hospitals? What are the FKs in each Table? What type of relationship notation is shown on the ERD? (tough question)
  58. 58. 58 ORDERS AND SHIPPING DATABASE ERD Task: Discuss PK and FK in each Entity (Table). Discuss Relationships that exist between "EACH PAIR OF ENTITIES (Tables)"
  59. 59. 59 1:M (OR M:1) RELATIONSHIP
  60. 60. 60 ERD AND TABLES
  62. 62. 62 INTERSECTION TABLE AND COMPOSITE KEY (ERD) A composite key is two or more fields used to define a primary key in a table.
  63. 63. 63 INTERSECTION TABLE AND COMPOSITE KEY (TABLE) A composite key is two or more fields used to define a primary key in a table.
  64. 64. 64 RDBMS DML: Data Manipulation Language DDL: Data Definition Language Metadata: Data about data Data Schema: Design of the data (supported by an ERD) DBMS vs. Database
  65. 65. 65 REFERENCES (2020).—free flowchart maker and diagrams online. Retrieved November 23, 2020, from SQLite Browser. (2020, November 09). DB Browser for SQLite. Retrieved November 23, 2020, from SQLite. (2020). SQLite Main Website. Retrieved November 23, 2020, from McFarland, R. (2020). Published Articles: Ron McFarland. Retrieved December 03, 2020, from Tutorialspoint. (2020). SQLite Tutorial. Retrieved November 23, 2020, from Watt, A. and Eng, W. (2020). Database Design, 2nd edition. Licensed under Creative Commons Attribution 4.0. Matthew West and Julian Fowler (1999). Developing High Quality Data Models. The European Process Industries STEP Technical Liaison Executive (EPISTLE).
  66. 66. 66 INTRODUCTION Ron McFarland Technologist, Educator Source: Microsoft Images
  67. 67. 67 ABOUT THIS COURSE This course is distributed free. I use several sources. But importantly, I use the book noted on the next slide. If you are using these PowerPoints, please attribute Highervista, LLC and me (Ron McFarland). IN ADDITION, please attribute the author noted on the next slide, as the author’s textbook provides essential information for this course. Source: Microsoft Images
  68. 68. 68 INTRODUCTION This course is offered to you free. HOWEVER, please purchase the following book, as it is a primary resource for this course. I do not make any $ from this course or this book. So, since a handful of good content is derived from the following text, please support this author! Title: SQL Quickstart Guide Author: Walter Shields Available: Amazon, B&N, and through ClydeBank media website at: tech/sql-quickstart-guide