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ความรู้เบื้องต้นฐานข้อมูล 1

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ความรู้เบื้องต้นฐานข้อมูล 1

  1. 2. <ul><li>A database is a structured collection of records or data . </li></ul>
  2. 3. <ul><li>Database management systems (DBMS) are the software used to organize and maintain the database. Example is MS Access, SQL Server </li></ul>
  3. 4. <ul><li>Early 1970 the Database was used term in Europe and USA. </li></ul><ul><li>1960s, the first developed DBM by Charles Bachman. </li></ul><ul><li>1970, the relational model was proposed by E. F. Codd. </li></ul><ul><li>1990s, attention shifted to object-oriented databases. </li></ul><ul><li>2000s, the fashionable area for innovation is the XML database </li></ul>
  4. 5. <ul><li>Bit </li></ul><ul><li>Byte </li></ul><ul><li>Field </li></ul><ul><li>Record </li></ul><ul><li>File </li></ul><ul><li>Entity </li></ul><ul><li>Attribute </li></ul><ul><li>Primary Key </li></ul><ul><li>Foreign Key </li></ul><ul><li>Field Type </li></ul>
  5. 6. <ul><li>A bit is a binary digit, taking a value of either 0 or 1. </li></ul>
  6. 7. <ul><li>A byte is a unit of measurement of information storage, most often consisting of eight bits. </li></ul>
  7. 8. <ul><li>1024 bytes= 1KB </li></ul><ul><li>1024 KB = 1MB </li></ul><ul><li>1024 MB = 1GB </li></ul><ul><li>1024 GB = 1 Terabyte (TB) </li></ul><ul><li>Petabyte </li></ul><ul><li>Exabyte </li></ul><ul><li>Zettabyte </li></ul><ul><li>Yottabyte </li></ul><ul><li>Brontobyte </li></ul>
  8. 9. <ul><li>One or more related characters treated as a unit and constituting part of a record. </li></ul>
  9. 10. <ul><li>A group of related data, words, or fields treated as a meaningful unit. </li></ul>
  10. 11. <ul><li>A group of records in database. </li></ul>
  11. 12. <ul><li>an entity is an existing or real thing. </li></ul><ul><li>Example: Customer, Student, Item </li></ul>
  12. 13. <ul><li>an attribute is an specification that defines a property of an object, element, or file. </li></ul><ul><li>Example: </li></ul><ul><li>Customer </li></ul><ul><li>Attribute: Title, Firstname, Lastname, </li></ul><ul><li>Address, Telephone, Email </li></ul>
  13. 14. <ul><li>Primary key is that candidate key which is used to uniquely identify each and every attribute and instance of a particular entity. </li></ul><ul><li>Example – Purchase Order Master Table </li></ul>
  14. 15. <ul><li>A Foreign key is an attribute in some another entity which is already a primary key in some entity. Is used for the purpose of maintaining the integrity of the data. </li></ul><ul><li>Example – The Purchase Order Master and the Purchase Order Detail Relationship. </li></ul>
  15. 17. <ul><li>Text. Essentially the strings or number. 255 character maximum. </li></ul><ul><li>Number. This category includes Byte (unsigned 8-bit), Integer (signed 16-bit), Long (signed 32-bit), Single (signed 32-bit), and Double (signed 64-bit). </li></ul>
  16. 18. <ul><li>Currency. A 64-bit fixed point number, designed to give the accuracy needed for financial data. 15 digits of whole dollars, plus four decimal places (hundredths of a cent). </li></ul><ul><li>The AutoNumber is an automatically assigned number. </li></ul>
  17. 19. <ul><li>Date/Time. The 8-byte floating point numbers, the integer part refers to the day, and the fraction part refers to the time. </li></ul><ul><li>Yes/No. A Logical field can be displayed as Yes/No, True/False, or On/Off. </li></ul><ul><li>Memo. Many texts. Up to 64K of text. </li></ul>
  18. 20. <ul><li>OLE Object. Use this type to store pictures, audio, video, or other BLOBs (Binary Large OBjects). </li></ul>
  19. 21. <ul><li>User </li></ul><ul><li>Operator </li></ul><ul><li>System Analyst </li></ul><ul><li>Programmer </li></ul><ul><li>Database Administrator </li></ul>
  20. 23. <ul><li>It defines a set of operations that can be performed on the data. </li></ul>
  21. 24. <ul><li>Hierarchical database model </li></ul><ul><li>Network database model </li></ul><ul><li>Relational database model </li></ul><ul><li>Object database models </li></ul>
  22. 25. <ul><li>Alternative </li></ul><ul><ul><li>Star schema </li></ul></ul><ul><ul><li>XML database </li></ul></ul>
  23. 26. <ul><li>hierarchical database model , data is organized into a tree-like structure. The structure allows repeating information using parent/child relationships: each parent can have many children but each child only has one parent. </li></ul>
  24. 28. <ul><li>network model is a database model conceived as a flexible way of representing objects and their relationships. the network model allows each record to have multiple parent and child records </li></ul>
  25. 30. <ul><li>A relational database model developed by E.F. Codd. A relational database allows the definition of data structures, storage and retrieval operations and integrity constraints. In such a database the data and relations between them are organised in tables . A table is a collection of records and each record in a table contains the same fields . </li></ul>
  26. 32. <ul><li>A data model is a logic organization of the real world objects (entities), constraints on them, and the relationships among objects. A DB language is a concrete syntax for a data model. A DB system implements a data model. </li></ul>
  27. 34. <ul><li>The star schema is the simplest style of data warehouse schema. The star schema consists of a few &quot;fact tables&quot; (possibly only one, justifying the name) referencing any number of &quot;dimension tables&quot;. </li></ul>
  28. 36. <ul><li>An XML database is a data persistence software system that allows data to be stored in XML format. </li></ul><ul><li>XML Format </li></ul><ul><ul><li><firstname> Witoon </firstname> </li></ul></ul><ul><ul><li><lastname>Thammatuch-aree</lastname> </li></ul></ul>
  29. 37. <ul><li>One to Many </li></ul><ul><li>Many to One </li></ul><ul><li>One to One </li></ul><ul><li>Many to Many </li></ul>
  30. 38. <ul><li>One to Many relationship – occurs when one entity is related to many occurrences in another entity. For example, one club has many members. </li></ul>
  31. 39. <ul><li>A Many to One relation is the same as one-to-many, but from a different viewpoint. </li></ul>
  32. 40. <ul><li>A one-to-one relation is exception in databases. It can occur, but it's often a sign that the database design has opportunities for improvement. </li></ul>
  33. 41. <ul><li>Many to Many relationship – occurs when one entity is related to many occurrences in one entity. For example, one newspaper has many readers and one reader has many newspaper. </li></ul>
  34. 42. <ul><li>Avoid Inconsistency </li></ul><ul><li>Data Sharing </li></ul><ul><li>Reduce Redundancy </li></ul><ul><li>Data Integrity </li></ul><ul><li>Data Security </li></ul><ul><li>Application and Database </li></ul>
  35. 44. <ul><li>Create Table and Relation for: </li></ul><ul><ul><li>Group A = Customers </li></ul></ul><ul><ul><li>Group B = Suppliers </li></ul></ul><ul><ul><li>Group C = Employees </li></ul></ul><ul><ul><li>Group D = Items </li></ul></ul><ul><li>Field name, Field type, Field size, Primary Key </li></ul>