LU04.S07 - ERD: Reingineering of an existing database [BZZ

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====== LU04.S07 - ERD: Reingineering of an existing database  ======

===== Task  =====
Go to the W3Schools-Website, to the SQL-Editor, and analyze the existing data-structure. Create furthermore an ERD, that describes the existing data-structure in the Crow's Foot Notation.

===== Suggested approach=====
  - We beginn the diagramm by identifying the entities. these are tables without any foreign keys: 
      * Customers
      * Categories
      * Employees
      * Shippers 
      * Suppliers
  - Then we determine the attributes and the data-types of each entity (-table).
  - We continue with the analysis of the relations. These are tables, which have foreign keys in their attribute list.
     * Orders
     * OrderDetails
     * Products  
  - Finally, we connect the tables with each other in the right fashion and determine the cardinalities (1:1, 1:n, n:m)


===== Solution =====
{{:modul:m290:learningunits:lu03:loesungen:l07.drawio2.png?1500|}}

===== Vocabulary =====
^ English ^ German ^ 
| prerequisite | Grundvoraussetzung |
| given| gegebene, vorausgesetzt |
| to determine | bestimmen |
| suggested approach | Vorgehensvorschlag |


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[[https://creativecommons.org/licenses/by-nc-sa/4.0/|{{https://i.creativecommons.org/l/by-nc-sa/4.0/88x31.png}}]] Volkan Demir