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 Yearling
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Apr
21
comment I'm a beginner, studying Data modelling as part of my course. I'm having trouble understanding Normalisation. How can i improve?
Bottom up means starting with a proposed solution, at the detailed level, and working your way backwards to the big picture. Bottom-up design is a little like reverse engineering.
Apr
20
comment I'm a beginner, studying Data modelling as part of my course. I'm having trouble understanding Normalisation. How can i improve?
en.wikibooks.org/wiki/A-level_Computing/AQA/…
Apr
20
comment I'm a beginner, studying Data modelling as part of my course. I'm having trouble understanding Normalisation. How can i improve?
Realize that normalization is a bottom-up design technique, not a top-down one. In the process of coming up with a new design, it's useful as one way of cross checking a proposed design. But not all normalized designs are good designs, nor are all good designs normalized ones.
Apr
20
comment I'm a beginner, studying Data modelling as part of my course. I'm having trouble understanding Normalisation. How can i improve?
+1 for emphasizing understanding the data.
Apr
7
revised How could DBAs be more 'programmer friendly'?
edited body
Mar
23
answered How to show the Join with Crows Foot Notation
Feb
27
awarded  Yearling
Feb
24
comment Postgresql inheritance based database design
Looks good to me.
Feb
24
comment Postgresql inheritance based database design
Weird constraint names were also a feature of the RDBMS I used, back in the day.
Feb
24
comment Postgresql inheritance based database design
you are right: I misunderstood your children question. I also didn't undertand whether you were talking about parent-child as people or whether you were speaking generically about one-to-many relationships, or so called "has-a" relationships. Whether the parents and the children belong in the same table or different tables depends on whether we model them as the same type or different types (or maybe subtypes as in the prior discussion).
Feb
24
comment Postgresql inheritance based database design
The performance considerations are these: joins are costly, although less costly than most newbies think. The right indexes, and a well optimized DBMS make all the difference. Fat tables are costly, because it costs more to read each row, even when most of the data won't be used. There's a trade-off between skinny tables and few joins. All of this is DBMS specific, but a lot of products follow this general pattern.
Feb
24
comment Postgresql inheritance based database design
In every parent child relationship I've ever dealt with, the advantages were on the side of single table inheritance. Basically, the attributes were almost all common attributes, and NULLS were not a concern. You still have to do a join to form an "all my children" query. The FK in this case is a dependent attribute that references a different row in the same table. and people who are nobody's child (in the database) have a NULL inthe FK. YMMV.
Feb
24
revised Postgresql inheritance based database design
share primary key para added.
Feb
24
answered Postgresql inheritance based database design
Feb
23
answered Modeling a product database and dealing with inheritance
Feb
23
comment Normalisation to 3NF
What have you tried so far?
Feb
20
revised What's the point of the relationship diamond in Entity-Relationship diagrams?
typo
Feb
20
answered What's the point of the relationship diamond in Entity-Relationship diagrams?
Feb
8
answered In a one-to-one relationship, where should the foreign key be placed?
Feb
6
revised Survey Database - Respondent Table (1NF or 3NF - Pros and Cons)
added 26 characters in body