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Published byClemence Clarke Modified over 9 years ago
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A collection of data organized in a way that allows: Easy access Easy retrieval of specific data Easy use of the data
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First, consider what you want the database to do for you. Database design is arranging information into tables and fields.
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What tables will be needed? Consider the types of information that will be used: employees, inservice classes, attendance at inservices. Will there be primary keys? Are there any extra fields needed? Are there relationships among the fields? What are the types of data in each field?
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Is there duplicated data between tables? It can cause problems when updating It wastes space It could make data inconsistent Where will the database be stored?
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Minimizes duplicated data Info is more accurate and consistent Easier to enter data using forms Easier to view and sort info in many different ways Easier to add passwords and use security features Easier to share and edit information at the same time with other database users
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Names can be 64 characters long Names can include letters, numbers, spaces and most types of punctuation Names cannot contain periods, exclamation points, access graves or brackets Field names cannot be duplicated
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Our database will include: Information about employees Information about Inservices Classes offered Information about attendance at these classes
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Employee Social Security Number for the employee table would be reasonable. Due to privacy and identify theft, we will assign each employee an employee ID number.
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Employee Table See “Employees” Excel spreadsheet Need fields for each of the columns contained in the spreadsheet Inservice Classes Table Each class will be assigned a Class No. See Inservices Classes Table to identify fields needed Inservice Attendance Table ID No. for each “transaction” Employee ID No. Inservice Class No.
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To keep from duplicating information, we’ll create relationships between the three tables. One employee can attend many inservice classes. One inservice class can be attended by many different employees.
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Look at the Employees Excel spreadsheet. Determine the data type for each of the columns. Three most common data types: Text – can contain up to 255 characters (wow!) Number – can be only positive or negative numbers. To use data in mathematical operations, it must be identified as a number. Currency – only monetary data. Will contain $ signs, commas, decimals points, and 2 decimal places. Can be used in mathematical calculations.
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Review tables and fields. Is there information that is duplicated between tables? If so, it will make it more difficult to correct errors, take up more disk space, etc.
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