Tuesday, January 21, 2014

Computers

Normalization Normalization is a method for organizing selective teaching elements in a infobase into panels. Normalization Avoids Duplication of Data The same data is nominateed in multiple lines of the database Insert anomalousness A portray active an entity bunsnot be inserted into the table without first inserting in coordinateation around other entity Cannot enter a guest without a glaring sales effect take away Anomaly A record cannot be deleted without deleting a record about a related entity. Cannot delete a sales order without deleting totally of the customers info. Update Anomaly Cannot update information without changing information in many places. To update customer information, it must be updated for each sales order the customer has placed Normalization is a three stagecoach bear upon After the first stage, the data is said to be in first normal form, after the plunk for, it is in flake norma l form, after the third, it is in third normal form in the lead Normalization 1. Begin with a list of all of the fields that must appear in the database. turn over of this as wiz life-size table. 2. Do not embarrass computed fields 3. One place to dismount getting this information is from a printed inscription used by the system. 4. Additional attributes in addition those for the entities described on the document can be added to the database.
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before Normalization Example See Sales severalise from downstairs: [pic] Fields in the original data table get out be as follows: Sa lesOrderNo, Date, CustomerNo, CustomerName, ! CustomerAdd, ClerkNo, ClerkName, ItemNo, Description, Qty, UnitPrice Think of this as the baseline one large table Normalization: First Normal family reprint Repeating Groups into New Tables. Repeating Groups Fields that may be repeated several times for one document/entity reach a new table containing the repeating data The primary signalize of the new table (repeating group) is always a composite primal; Usually document...If you want to get a full essay, order it on our website: OrderCustomPaper.com

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