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Should a primary key ever change?
While there is nothing that will prevent you from updating a primary key (except integrity constraint), it may not be a good idea: From a performance point of view: You will need to update all foreign keys that reference the updated key. A single update can lead to the update of potentially lots of tables/rows.
Can primary key values be repeated?
No, it is not possible in SQL Server to insert records that have duplicate values in the Primary Key. It is not possible to have more than one row in the same table with the same primary key (PK).
Should primary keys be immutable?
The primary key should be immutable, meaning that its value should not be changed during the course of normal operations of the database. (Recall that a primary key is the means of uniquely identifying a tuple, and that identity, by definition, never changes.)
What is the rule of primary key?
Primary keys should be immutable, that is, never changed or re-used; they should be deleted along with the associated record. Primary keys should be anonymous integer or numeric identifiers.
How are primary keys different from other keys?
A primary key is just one among several “candidate” keys (several possible identifiers in a database table). The primary key doesn’t necessarily require any fundamentally different property to any other key so assertions and design principles that apply specifically to primary keys and not to other keys are always suspect and often wrong.
Is there a problem with the term primary key?
The problem / misunderstanding implicit in your question is due to inappropriate use of the term primary key. A primary key is just one among several “candidate” keys (several possible identifiers in a database table).
Do you need a primary key for craete?
Data that won’t be updated or deleted, and wont be constrained in any way. Essentially structured logging. A primary key will always help with query performance. So if you ever need to query using the “key” to a “foreign key”, or used as lookup then yes, craete a foreign key.
Do you need a primary key in a database?
No, unless you can find an example of, “This database would work so much better if table_x didn’t have a primary key.” You can make an arguement to never use a primary key, if performance, data integrity, and normalization are not required.