A type of integrity constraint used in a RDBMS platform to ensure that a value in a column matches one of a range of key values from another table.
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1answer
755 views
Is using multiple foreign keys separated by commas wrong, and if so, why?
There are two tables: Deal and DealCategories. One deal can have many deal categories.
So the proper way should be to make a table called DealCategories with the following structure:
DealCategoryId ...
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2answers
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What is the purpose of SET NULL in Delete/Update Foreign Keys constraints?
I am probably being narrow minded, but if I create a foreign key constraint and a row gets updated or deleted, I lose that connection if the child table's column gets set to NULL.
What is the purpose ...
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Are there any database engines which will intuit the join condition based on the existing foreign keys?
It seems strange to me that, when I've defined a foreign key, the engine cannot use this information to automatically figure out the correct JOIN expressions, but instead requires me to re-type the ...
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2answers
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Non-unique multicolumn foreign key
I have a "comments" table that models a conversation on a topic, like this:
id serial
topic_id integer
parent_comment_id integer
body text
So, every comment has a reference to its topic AND ...
3
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2answers
178 views
Both Primary and Foreign Key Needed on Table?
Someone recently asked this question:
There are two tables: Deal and DealCategories. One deal can have many
deal categories.
So the proper way should be to make a table called ...
3
votes
1answer
602 views
Foreign Key constraint on fixed value field
Note: I am a developer...
I have an Asset table that has many codes that are foreign keys into a second table OutlineFiles. The OutlineFiles table has Type and Code as the primary key. The foreign ...
