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Database

Database. Lesson 02 – Database Development. Overview. Data Dictionary. Tables and Forms. Data Dictionary. Data dictionary is description of each field in a database. Field name – is name of the field Data type – is the kind of data in the field.

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Database

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  1. Database Lesson 02 – Database Development Q.Nand

  2. Overview • Data Dictionary. • Tables and Forms. Q.Nand

  3. Data Dictionary • Data dictionary is description of each field in a database. • Field name – is name of the field • Data type – is the kind of data in the field. • Field size - is the number of characters allowed in each field. • Description - specifies the contents of the field. Q.Nand

  4. Field Name • Relatively short • Clear Q.Nand

  5. Data Type • Text • Used for text or numbers that do not require calculations, such as phone number. • Eg: • (02) 9735 7563 • Adams David • Memo • Used for lengthy text and numbers. • Eg: • Description • Number • Used for numeric data to be included in mathematical calculations. • Eg: 1235 Q.Nand

  6. Data type (Cont…) • Currency • Used for currency values • Eg: $ • AutoNumber • Used to automatically create a unique number when a record is added. • Yes/No • Used for data that can be only one of two possible values. • Eg: Checked list. Q.Nand

  7. Data type (Cont…) • Date/Time • Used for dates and times. • OLE object • Used for data created in other programs such as spreadsheet graphic or sound. • Hyperlink • Used for hyperlinks to link from 1 slide to another or to different file. Q.Nand

  8. Field Size Number of characters allowed in each field. eg: Phone number = 02 9465 8364 Q.Nand

  9. Description specifies the contents of the field. Q.Nand

  10. Tables • A table or a list displays data using: • Columns as Field and • Rows as Records Column Row Q.Nand

  11. Form • A form or label usually displays data for every field of a single record. • The layout of a form can be changed. Q.Nand

  12. Exercise 02 • Define ‘data dictionary’ • Explain why the data dictionary is such an important part of a DBMS. • Propose why it would be better to store a telephone number as text rather than as a number data type. • Explain the difference between a table and a form. • What data type am I? a) Numeric data to be included in mathematical calculations. b) Data that can be only one of two possible values. c) Data used for text or numbers that does not require calculations. d) Data created in other programs. Q.Nand

  13. Dictionary • Field name • Field size • Description • Data type • Table • Form Q.Nand

  14. References • G.K. Powers. “Information and Software Technology”. • Jacaranda. “IST Information and Software Technology”. Q.Nand

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