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Nov
5
comment Database Design for Paper Submission System
@IrfanAliMemon In the ERD with four tables, SUBMISSION records the act of a paper being submitted. Assuming the editing process may sometimes involve rejection(s) and resubmission(s) this is 1:M with PAPER. For each such act of submitting a paper, there may be a different list of AUTHORs - which is M:N with SUBMISSION. This M:N relationship is resolved with the CONTRIBUTION table.
Nov
4
comment How to insert values in junction table for many to many relationships?
@xyz Having implicit COMMIT is not the same thing as never having or wanting to control you transaction scope. When you are writing into multiple tables in a single logical unit of work you will want to control your transactions explicitly
Nov
3
reviewed Approve Are bitemporal tables convenient, compared to valid-time and transaction-time tables separately?
Nov
3
answered Composite Foreign key to single primary key
Nov
2
revised Preventing duplicate data when usual normalization only makes sense for some of the records
Expanded and clarified.
Nov
2
answered Preventing duplicate data when usual normalization only makes sense for some of the records
Nov
2
answered How to insert values in junction table for many to many relationships?
Nov
2
answered Database Design for Paper Submission System
Oct
18
answered Can't finish my ER diagram
Oct
17
comment Why does a UNIQUE constraint allow only one NULL?
Semantically there is a huge difference between Null (don't know) and Null (don't care). Not making a distinction between these in either the standard or the various implementations makes for a lot of resulting confusion. You could say that all "null/don't know" are equal but all "null/don't care" are distinct, for example. It makes for strange, arbitrary implementation decisions by each RDBMS builder.
Oct
17
comment Can't finish my ER diagram
You should go and take a closer look at the ERD reference that you linked. I'm pretty sure you have the crow's foot backwards for what you intend. Your diagram says "a book has one or more publishers" (which may be true in some real world scenarios) but it also says: "a publisher publishes (exactly) one book" which I'm sure you didn't mean. Same thing for members renting and authors writing.
Oct
9
answered ERD Design for Employee Leave
Sep
30
awarded  Explainer
Sep
30
comment Supertyping Inventory Transactions
Agreed. Further to this, if you think you really want to run queries against one particular transaction type, create views on the transaction table(s). If the big table with nulls approach is used, the views on the table will almost certainly be writable as well.
Sep
28
comment Database design : hotel room and its detail
Room type and room size on a room description table might violate 3NF if the type and size depend on the room, not on the description of the room. You don't state your assumptions about dependencies, you just split a bunch of properties of rooms off from the rooms table in a way that might be creating transitive dependencies. Your inference of my logic is in exactly the opposite direction.
Sep
28
reviewed Close get mysql index size split by index
Sep
28
reviewed Leave Open MySQL lost connection
Sep
28
awarded  Custodian
Sep
28
reviewed Leave Open Disaster Recovery Options for Sql Server
Sep
28
reviewed Close CROSS JOIN and updatable model design for Ruby on Rails