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Questions tagged [composite-primary-key]

Composite primary key is a primary key, which consists of more than one column. The column combination guarantees the uniqueness of the PK.

A Composite Primary Key is a Composite Key, which is assigned as Primary.

Primary key is a single field or the least combination of fields that uniquely identifies each record in table. When the primary key consists of more than one field, when we are talking about composite primary key. Composite or not, is the most appropriate key to be main key of reference for the table.

The primary key must not be null and must contain only unique values.

Primary keys are mandatory for every table. When choosing a primary key from the pool of candidate keys, always choose a single simple key over a composite key.

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sqlite3 foreign key

I have a database made in sqlite3 and have set foreign keys on the loan table to the student table and book table to stop duplicate loans: using create table: CREATE TABLE loan( SudentID INTEGER, ISBN INTEGER, out INTEGER, FOREIGN…
Timothy Lawman
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Oracle COLUMN_ID implicit index creation

How does Oracle use COLUMN_ID as found in USER_TAB_COLUMNS view? I just need to confirm that it does not use this internal column ordering while creating implicit indexes - such as when a primary key is enforced or a unique key constraint is created…
Senthu Sivasambu
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Active Record: Implicit value for part of multi column belongs_to key

We have multiple lists of shops from different data sources that have to be matched. The shops have a composite primary key [source, id]. The matching creates a separate entry in the shops table with source=0 and extracts values (name, url, ...)…
Jan
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What is the difference in perfomance of using composite primary key vs simple index?

I'm using innodb mysql tables for storing data. In my project i have to store maxmind geoip database in mysql (to have native foreign keys with different entities). Most tutorials how-to import maxmind geoip database in mysql advice following table…
avasin
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update from another table with 2 primary keys

i have two table T1 & T2 with same columns (service, desti,...) composite primary key on T1 (service, desti) I want to update t1 as data in t2. Plz advise, Thanks in advance
user209943
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Database composite key in MySql

Condition is Each operator record has a unique group code and product code. It may possible that some group has same product code. main operator table id integer PK name varchar(100) product group…
Mayank Pandya
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Join limit in mysql for tables having different column count

I am trying to join 20 table with almost 6 joining condition between each tables. Each table has differenct coulmn count approx 280. each table has four composite primary key.Common for all 20 tables. While executing query not able to get the column…
Mohan
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Entity class with a composite primary key doesn't have getter and setter

I have an entity class userdetails which has the username, userid (numeric) and password fields, with username and userid forming a composite primary key. This is negotiable, and possibly unimportant to the main problem. I have another class,…
AodhanOL
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Dropping Unique index and setting same fields to be the Primary Key

I have a 5GB that has 3 columns as a unique (non-clustered) index. I want to promote these three to be the new primary key (clustered). Should I drop this index before change the PK? Also I am planning on dropping this index after I change the PK.…
James A Mohler
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Using MVC4 Database-first, how to annotate models with a composite primary key?

I am new to MS's MVC4, and I have been given a database for which I must build a CRUD front-end. The tables all have composite primary keys of the form [TableID, TableName, EffectiveDate]. I cannot alter the database design. I used the…
JohnG
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Composite primary keys with PetaPoco for Exists and GetById methods

I found this nice branch of PetaPoco by schootime which handles composite primary keys. Now what I didn't find is how he handled in his version of PetaPoco methods which require a primary key, with composite keys like for example db.Exists and…
Manight
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How can I insert data into a table that has a composite primary key through JPA?

User Table UserName pk fname lname GroupMaster GroupName pk UserName pk, fk I want to insert data in GroupMaster but my problem is it has composite primary key How can I insert data in table through entity manager object?
Hirren Gamit
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SQL Query -- IF X is shared between two strings in a primary composite key?

Not sure how to explain this, as I have only basic SQL knowledge. I need help with some logic to signal a user when a unique string is referenced more than once in a composite primary key. A table I use contains a composite primary key which ties a…
table_formatter
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Why is MySQL not using composite key in range query?

I've checked numerous other SO posts and MySQL docs but can't seem to get an answer on why an index isn't being used, and how to force it to be used - I can see many others are having similar problems, but can't find a solution. The table looks like…
spooky
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JPA - Real primary key generated ID for references

I have ~10 classes, each of them, have composite key, consist of 2-4 values. 1 of the classes is a main one (let's call it "Center") and related to other as one-to-one or one-to-many. Thinking about correct way of describing this in JPA I think I…
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