Top "Primary-key" questions

When should I use primary key or index?

When should I use a primary key or an index? What are their differences and which is the best?

sql primary-key indexing

How to create foreign key that is also a primary key in MySQL?

This should be a fairly straightforward question, but I'm unable to find an easy answer. How do you create a …

mysql inheritance foreign-keys primary-key

When does the JPA set a @GeneratedValue @Id

I have a simple JPA entity that uses a generated long "ID" as its primary key: @Entity public class Player { …

java jpa primary-key

Change primary key in PostgreSQL table

I have users table in my PostgreSQL 9.3.6 database with two columns: id and another_id. The id is a primary …

postgresql primary-key

Referencing a composite primary key

I have two tables, with each table having a composite primary key. One attribute is in both composite primary keys. …

sql oracle foreign-keys primary-key composite-primary-key

database: primary key, Clustered or NonClustered

I am creating a database in SQL server 2008, CREATE TABLE Users ( U_Id INT NOT NULL FirstName VARCHAR(50) NOT NULL, …

database sql-server-2008 primary-key clustered-index

Can we use Guid as a Primary Key in Sqlite Database

Is is possible to use GUID as primary Keys in SQLITE Database?If Possible which datatype can be used?

android sqlite primary-key guid uuid

What is the difference between a primary key and a unique constraint?

Someone asked me this question on an interview...

sql primary-key

I need to auto_increment a field in MySQL that is not primary key

Right now, I have a table whose primary key is an auto_increment field. However, I need to set the …

mysql primary-key auto-increment

mysql Multiple Foreign Keys in a Table to the Same Primary Key

I have a table user with userID as the primary key. I have another table called Friends. In the Friends …

mysql sql foreign-keys primary-key referential-integrity