Facilities provided by a database management system to ensure consistency within the data.

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3
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2answers
271 views

Finding violations of the symmetry constraint

Suppose I have a table Friends with columns Friend1ID, Friend2ID. I chose to represent each friendship with two records, say (John, Jeff) and (Jeff, John). Thus, each pair of friends should show up ...
1
vote
1answer
1k views

Issues on defining a PK on a nvarchar column and indexing the FK referring this PK

Someone from the team, has defined two reference tables with a few records in each, and has defined the PK of these tables on a column of type nvarchar(255). The value exists in this columns are ...
5
votes
3answers
2k views

Lookup table for a one-to-many relationship

I have a tickets table with an id that I need to associate to a lookup table where the counterpart of that data is another id that is controlled from an outside source. tickets - id - sutff lookup - ...
2
votes
1answer
259 views

Representation of circular references constraint

We have a database where we store commands and properties for devices that may be controlled via a network. For instance, "Concrete Device" is an instance of some DeviceType, which in turn contains ...
5
votes
2answers
532 views

Help with good RDBMS transactional schema design that mimicks a sports league

I need to design a data model for a typical RDBMS that will mimic the structure of your typical sports league. Architecturally my requirements are: Well normalized Transactional Application ...
1
vote
2answers
5k views

set integrity not enforced in DB2

I am a bit confused with the SET INTEGRITY concept in DB2, why we can OFF the set integrity check to put the table in PENDING state ? does that mean that we can neglect the constraint definitions on ...
0
votes
1answer
73 views

Unknown relationship

I have a problem with a database design: I have an EReport. This EReport will have a QAPCategory. User must select a QAPCategory from an set of QAPCategory. To know which QAPCategory can be ...
17
votes
5answers
4k views

Are there DBMS that allow a Foreign Key that References a View (and not only base tables)?

Inspired by a Django modeling question: Database Modeling with multiple many-to-many relations in Django. The db-design is something like: CREATE TABLE Book ( BookID INT NOT NULL , BookTitle ...
2
votes
3answers
6k views

Truncate parent table in Oracle when child table is empty

Suppose I have a parent table parent referenced by a child table child. The table parent is populated but child is not. Attempting to truncate parent results in ORA-02449: unique/primary keys in ...
3
votes
1answer
131 views

Relationship with a default value

Firstly, I know my title is somewhat misleading, but I couldn't think of a better title. Here is my current relationship CREATE TABLE Events ( ID INT IDENTITY(1,1) NOT NULL, Name ...
4
votes
2answers
3k views

Do I need a separate Id column for this “mapping” table?

I have a table of Producers and a table of Products, both of which are of the form: Id - int, Primary key Name - nvarchar A Producer can carry multiple Products, so I was going to create a table ...
3
votes
3answers
521 views

How to maintain referential integrity of an object graph when a node is deleted

In a relational database, if a node in an object graph is deleted, how can the object graph's referential integrity be maintained? For example: A product is deleted, how is the invoice containing ...
5
votes
2answers
254 views

How should an object that can reference an object of multiple types be modeled in a relational schema?

Apologies for the obscure question, it may make more sense with a concrete example: In my application, I may create a portfolio that contains a set of projects. However, I may also add a ...
2
votes
3answers
564 views

SQL Server 2008r2 replication from multiple sources

I am currently rearchitecting an application so that each of seven businesses will have there own "live" SQL Server 2008 database and at scheduled times during the data the data from all seven ...
3
votes
2answers
2k views

How to select a subset of data from a large ER model?

I have a quite large ER model in my database and lots of data. Now I would like to take a subset of this data into a different database for testing purposes. The problem is how to get a subset from ...
25
votes
13answers
13k views

How to implement a 'default' flag that can only be set on a single row

For example, with a table similar to this: create table foo(bar int identity, chk char(1) check (chk in('Y', 'N'))); It doesn't matter if the flag is implemented as a char(1), a bit or whatever. I ...
7
votes
4answers
10k views

How do I identify tables that have a foreign key to a specific table in Sybase?

I am looking for (preferably) an SQL statement that selects the table/and column names for any table with a foreign key to a given table in Sybase. I think it should be somehow possible with the ...