Database diagram.

[tsvetkovd]

Please, anyone tell me what means a table to appear as an entity on the diagram? And how to identify the cardinality of a relationship and how to specify which is mandatory and which is optional, please? Thank you!

 

[jdraw]

Here is a set of video tutorials that goes through the whole process.
Entities, attributes, relationships, cardinality, optionality.....

These should be sufficient.


http://www.youtube.com/watch?v=IiVq8M5DBkk Logical data modeling

http://www.youtube.com/watch?v=BGMwuOtRfqU Candidate key

http://www.youtube.com/watch?v=ZiB-BKCzS_I Normalization

http://www.youtube.com/watch?v=pJ47btpjAhA Normalization example

http://www.youtube.com/watch?v=q3Wg2fZENK0 1st Normal form

http://www.youtube.com/watch?v=vji0pfliHZI 2nd Normal form

http://www.youtube.com/watch?v=HH-QR7t-kMo 3rd Normal form

http://www.youtube.com/watch?v=q1GaaGHHAqM E_R Diagramming

https://www.youtube.com/watch?v=lXAGQ8vmhCY <---new
Good luck.

 

[tsvetkovd]

Thanks a lot. Appreciate it!

 

[jdraw]

No problem, glad to help.

Cardinality is in the last video, as I recall.

 

[tsvetkovd]

Very helpful videos . I have one more question which I've been trying to solve. I need to implement an update in my database. I asked a friend, he said that it could be done by query. I need to use query to update the inspection frequencies for some of the bridge components. You will save my life if you tell me how can I do that!!! Thanks!

 

[jdraw]

http://www.w3schools.com/sql/sql_update.asp

http://www.youtube.com/watch?v=--PVVLIcbjE

Good luck