database design - Are composite primary keys bad practice?
Oct 21, 2017 · I want to know if composite primary keys are bad practice and if not, in which scenarios is their use beneficial? My question is based on this article Note the part about composite primary keys: ...
When should a primary key be declared non-clustered?
Nov 11, 2011 · Having a clustered index key with this low selectivity key as the leftmost key, e.g. , often makes sense because of ranges scans that look for all entries in a particular 'state'. One last note …
unique constraint - What is the difference between a primary key and a ...
Jul 20, 2014 · A Primary Key is a minimal Candidate Key, which is to say all constituent columns are strictly required in order to ensure uniqueness. As a database developer/designer of 30 years …
Differences between "Unique Key" and "Primary Key"
Mar 26, 2012 · Primary Key: Purpose of Primary Key is to act as a “KEY”. A primary key is a key in a relational database used to identify records. Unique Index: Unique Index is an “INDEX” intended for …
Difference between PRIMARY KEY and SERIAL (with index)
Aug 25, 2022 · a primary key constraint on the column that is implemented with the above index If you create the constraint, the index is created automatically. The constraint seems like an unnecessary …
Add autoincrement to existing PK - Database Administrators Stack …
Apr 23, 2017 · Also, make sure that the NEW table has a primary identity key added Note: This was necessary for me, since I used the good data with a primary key seeded, that was the correct …
sql server - How to avoid a "duplicate key" error? - Database ...
CONSTRAINT [PK_DeleteMe] PRIMARY KEY ([id] ASC)); Update From comments: Why do you have multiple sessions, which can obviously pull the same id from somewhere, using the same permanent …
Why does my table hold duplicate primary keys?
To my big (and worrying) surprise I just realized that my table with millions of rows, has a few handful of rows, where the primary key (ID) is a duplicate! I don't understand how this can ever hap...
How is this SQL Server PK violation possible?
Aug 4, 2017 · Violation of PRIMARY KEY constraint 'PK_IDMaster'. Cannot insert duplicate key in object 'IDMaster'. The duplicate key value is (25309587). This is due to locking; initially in the read …
performance - Guid vs INT - Which is better as a primary key ...
Use: a Key Mapping Table The TableA.ID is used locally in your database as the Primary Key, and the key to use for JOINing. TableAMap.ID is the same as TableA.ID, and TableAMap.UniversalID is …