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ER1-tute.pdf

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ISYS1055/1057 Tutorial Sheet The Entity-Relationship Model (1) 1. For each of the following description, complete tasks: a. Draw an ER diagram showing entities, attributes, and relationships and their multiplicity. Where necessary state any assumptions. b. Map the ER diagram into a relational database schema. Explicitly denote primary keys (underline) and foreign keys (asterisks *) for relations in the result
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  ISYS1055/1057 Tutorial Sheet The Entity-Relationship Model (1) 1.For each of the following description, complete tasks: a.Draw an ER diagram showing entities, attributes, and relationships and their multiplicity. Where necessary state any assumptions.  b.Map the ER diagram into a relational database schema. Explicitly denote  primary keys (underline) and foreign keys (asterisks *) for relations in the resultant schema. 1)Customers identified by a name and with an address purchase items. Items are identified by a number and have a colour . The quantity bought of each item is recorded. 2)An order with a unique number and date can be made for any quantity of parts, each with an item identifier and colour . Each order is made by one supplier with a name and address. 2.Consider the following description: Departments are identified by an ID and have budget. For each department there are several projects, which have a name and start date. Draw an ER diagram for the description and map it into a relational database schema. Explicitly denote primary keys and foreign keys of relations in the resultant schema. The ER diagram must use symbols in the lecture notes. You must use the ER drawing tools Dia (free). Dia can be downloaded from the course homepage.  Produce a pdf file containing your answers. On Dia, when exporting an ER diagram to a pdf file, first set up the “Page setup” to “fit to 1 by 1” so that the diagram scales well in the exported pdf file.  3. Given below is an ER diagram for a “Movies” database. a.Explain the assumptions made about the Borrow and Direct relationships in the ER diagram.  b.Map the ER diagram into a relational database schema, and clearly indicate the primary key and any foreign keys for each relation.
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