Reputation
7,195
Top tag
Next privilege 10,000 Rep.
Access moderator tools
Badges
1 9 23
Newest
 Explainer
Impact
~162k people reached

Aug
4
reviewed Approve sql-server-2012 tag wiki
Aug
4
reviewed Approve sql-server-2005 tag wiki
Aug
4
reviewed Approve IF IS NULL then SINGLE else keep the value of the field
Aug
4
reviewed Approve select rows where column contains same data in more than one record
Aug
2
answered Messaging Database - How to handle multiple recipients
Aug
1
comment Struggling with normalisation (database design critique)
The way you've pictured it works, as long as clients and sites can potentially have more than one contract and contracts are only ever for one site or one client. You also need to add constraints or logic to enforce that a contract is for either a client or a site. If these cardinality rules aren't what you intend, then you might need to change your design.
Jul
30
comment Conceptual model vs Logical model vs Physical model
What you're referring to on the Wikipedia page is the DDL (data definition language) that defines the physical schema in minute detail. DDL is one way to express the physical model - probably a very good way, since it is very precise. However, it is not the only way. You can express a physical model graphically, for instance.
Jul
28
comment Conceptual model vs Logical model vs Physical model
I don't think you're on the right track, exactly, especially with the conceptual model. See this answer for something which holds up pretty well, I think: stackoverflow.com/questions/4279089/…
Jul
28
reviewed Approve Decode Function in Oracle
Jul
14
revised Enforce referential integrity between two groups of data
Corrected spelling for clarity, especially in the title to improve searchability.
Jul
14
comment Enforce referential integrity between two groups of data
The problem is that a foreign key needs to reference all of the columns in the key. You are trying to reference part of a candidate key. Obviously that doesn't make sense. If your intersection table is truly referencing just the group IDs, then you need to normalize the rule and action tables to make their group IDs unique without reference to other columns.
Jul
12
reviewed Approve what is '#' in create table statement?
Jul
8
reviewed Approve Order by alphabet and then by numbers
Jul
5
comment Personal and Global messaging database design
You should see my answer to this question on Stack Overflow, where I go into quite a bit of detail for essentially the same requirement: stackoverflow.com/questions/6541302/…
Jul
4
answered Is there a good way to select a row where the key represents the lower bound of a range?
Jun
30
reviewed Edit Different type of column
Jun
30
revised Different type of column
added para pointing to the table inheritance tags in SO and comment from answerer.
Jun
29
answered Best relationship database design to manage types for different entities
Jun
27
comment Different type of column
@yannis - Hmmm, hard to find a really great link. The terminology is what's used in James Martin's Information Engineering(TM) method. Some others call it a classifying attribute. The topic to read up is Entity Subtyping - this will cover the various ways that you could implement this model physically. The point of the partitioning attribute is to help enforce mutual exclusivity of subtypes. Each subtype is associated with a particular data value in the partitioning attribute.
Jun
26
answered Different type of column