6,412 reputation
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bio website mooseware.ca
location Mississauga, Canada
age 52
visits member for 2 years, 11 months
seen 4 hours ago

I'm a professional software developer with more than twenty years of experience across many industries and the entire systems development lifecycle. I'm the principal consultant at Mooseware Limited.

@joelabrown

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May
24
comment I don't know how to read many to many relationships
It should be noted that the tutorial you cited gets the physical implementation wrong. The relationship from Project to ProjectEmployee should be 1:1,M not 1:0,M. The relationship from the intersection table to Employee is often read "is a".
May
22
comment How do I connect my MS Access database to the LAN?
This is not a duplicate question and it shows lack of understanding of the technology to mark it so. The referenced "original" question has one solution to what this question is asking, but it is by no means the only solution nor even necessarily, depending on the circumstances, a good solution.
May
21
reviewed Approve suggested edit on How do you re-sync the Master MySQL DB with Slave DB changes if the Master goes offline?
May
21
answered How do I connect my MS Access database to the LAN?
May
12
comment Airline reservation system
Unless you're doing this as a limited academic exercise, your model is much too simple. Flights can have multiple segments for example, e.g. one flight might be YEG-YYC-LAS and passengers. There may be passengers flying YEG-YYC and YEG-LAS and YYC-LAS, all on the same plane under the same flight number. Also, this same plane may be flying under multiple numbers because of code-sharing agreements where partner airlines both sell seats on the same flight. There are many other examples of how this model is not representative of real-world commercial airline scheduling.
Apr
23
comment Is this design in 3NF? Why to choose another design not in 3NF
@villamejia - Adding a single surrogate key to the intersection entity that implements a logical M:N is a difficult case. To answer your question directly, it is not a subject for normalization per se. There may be practical reasons for doing this, especially in the physical model and especially if the relationship itself is a parent of some third entity. However, I think it is often seen simply because some people dogmatically apply surrogate keys to every table in their database.
Apr
23
answered Is this design in 3NF? Why to choose another design not in 3NF
Apr
17
comment Advanced design question related to compound primary keys
Regarding surrogate keys in place of compound keys, there is no consensus on this. It is a holy war issue.
Apr
17
comment Advanced design question related to compound primary keys
The constraint you're proposing doesn't make any practical sense. If the relationship is between 'Product` and User why can only one user within a client be related? If products can only be selected once per client then why not relate at the client level?
Apr
15
revised Relations between a imeid, sim chip, and account from a cellphone company?
Fixed cardinality on one of the relationships in the ERD.
Apr
15
answered Relations between a imeid, sim chip, and account from a cellphone company?
Apr
15
comment Relations between a imeid, sim chip, and account from a cellphone company?
IMEI identifies a device. SIM cards have an ID number too (ICC ID). A phone number (SSID) is assigned to one SIM (at a time). So there are lots of layers of abstraction. A person holding a phone has a phone number, but only because the phone (IMEI) has a SIM (ICC) in it and the SIM is assigned a phone number (SSID). Since the mobile operator wants to get paid, the SSID is linked to an account (some operator-specific account ID scheme). Note that an account (might) have many phone numbers. Each phone number probably has one plan (at any given time).
Apr
8
comment Implementing voting system like reddit/StackExchange?
If you want to make it like StackExchange, you'd also have to include a date/time when the vote was recorded.
Apr
6
answered Does redundancy exists in this table?
Mar
30
comment 3 way junction table and redundant value
@caramel1995 - This happens automatically. You don't assign a quantity of two laptops, you assign 2 specific laptops. This would manifest itself as two records in EMPLOYEE_OWNS_ASSET or as two ASSETs with an FK to EMPLOYEE depending on how you model it.
Mar
30
comment Attempting to identify transitive dependency
@crm - Yes. Looks good now.
Mar
30
answered 3 way junction table and redundant value
Mar
30
revised How to scatter/arrange all the tables in database model (workbench)?
Removed database design tag. This isn't a design question it's a question about a tool.
Mar
28
comment Designing a reservation system schema
Unless your bookings are for very carefully regimented blocks of time (days, hours, half hours, etc.) you're really better off recording what is booked, not what's available. Do you have an efficient, set-based query for calculating what's available, such as one from the answers to this question: stackoverflow.com/questions/9604400/… ?
Mar
26
comment Problem with reaching second normal form in a database
@ypercube is right. Take repeating groups out to get to 1NF. You can't be 2NF if you aren't 1NF yet, regardless of the definition/test for 2NF.