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TSQLMan
Posting Yak Master
160 Posts |
 Posted - 2003-09-15 : 10:39:54
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| I am in the process of designing a database for a shipments application. I have a shipments table with seperate ID's that point to other tables, Each one of the these tables is linked to the shipment table by their primary key back to a key of the same name within the shipments table. eg. ShipmentID Shipment.TrainID (1 --- many) Train.TrainID Shipment.DestinationID (1 --- many) Destination.DestinationID I am wondering in what case would I want to link the shipments table to another table by ShipmentID. eg. ShipmentShipmentID (1 --- many) Analysis.ShipmentID Shipments.ShipmentsID (1 --- many) Destination.ShipmentIDIf I didn't make myself clear enough, please feel free to E-mail, or respond.Thanks, |
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JustinBigelow
SQL Gigolo
1157 Posts |
Posted - 2003-09-15 : 10:46:45
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| Shipment line items springs to mind.Shipment.ShipmentID -> ShipmentContents.ShipmentIDMOO,Justin"Look at it out there orbiting like it's so cool, we will rule it with an army of replicants!" |
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TSQLMan
Posting Yak Master
160 Posts |
Posted - 2003-09-15 : 11:50:35
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| Just found a good article on the Five Steps of Database Normalization. Think I answered my own question. That happens a lot especially when I talk to myself.1.) First Normal Form - Create a Primary Incremented Key for each table with more than one record. 2.) Second Normal Form - Create separate tables for sets of values that apply to multiple records. Relate these tables with a foreign key.3.) Third Normal Form - Eliminate fields that do not depend on the key. 4.) In a many-to-many relationship, independent entities can not be stored in the same table5.) Fifth Normal Form - The original table must be reconstructed from the tables into which it has been broken down. |
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DB Design - Which ID to use