Stack Overflow
Stack Overflow

Questions tagged [compound-key]

Questions regarding usage of compound key (specific composite key) in database

76 questions
198
votes
5 answers

SQLite table constraint - unique on multiple columns

I can find syntax "charts" on this on the SQLite website, but no examples and my code is crashing. I have other tables with unique constraints on a single column, but I want to add a constraint to the table on two columns. This is what I have that…
Rich
  • 36,270
  • 31
  • 115
  • 154
58
votes
5 answers

dplyr issues when using group_by(multiple variables)

I want to start using dplyr in place of ddply but I can't get a handle on how it works (I've read the documentation). For example, why when I try to mutate() something does the "group_by" function not work as it's supposed to? Looking at…
Marc Tulla
  • 1,751
  • 2
  • 20
  • 34
33
votes
2 answers

Compound/Composite primary/unique key with Django

How can you create models (and thus tables) with a compound (composite) primary/unique key using Django?
Viet
  • 17,944
  • 33
  • 103
  • 135
17
votes
6 answers

In a junction table, should I use a Primary key and a unique constraint, or a compound/composite key?

I have read through handfuls of what would seem to make this a duplicate question. But reading through all of these has left me uncertain. I'm hoping to get an answer based on the absolute example below, as many questions/answers trail off into…
user1447679
  • 3,076
  • 7
  • 32
  • 69
9
votes
2 answers

Compound keys in JPA

I want to make an entity that has an autogenerated primary key, but also a unique compound key made up of two other fields. How do I do this in JPA? I want to do this because the primary key should be used as foreign key in another table and making…
homaxto
  • 5,428
  • 8
  • 37
  • 53
9
votes
1 answer

Can not set java.lang.Integer field id to org.hibernate.id.IdentifierGeneratorHelper

I need to store some data in a MySQL-database using Jpa 2/Hibernate 3.5.1. For legacy reasons the table I want to store data in has a compound primary key. The first part of the primary key is of type INTEGER (auto-increment-value), the second part…
user506600
  • 91
  • 1
  • 2
9
votes
2 answers

In SQLAlchemy, how do I query composite primary keys?

I'm using SQLAlchemy to programmatically query a table with a composite foreign key. e.g.: CREATE TABLE example ( id INT NOT NULL, date TIMESTAMP NOT NULL, data VARCHAR(128) PRIMARY KEY (id, date) ) I'd like to take a list of values and get rows…
DaveA
  • 1,227
  • 2
  • 14
  • 19
7
votes
1 answer

How to handle compound keys with Spring Data JDBC

I'm trying to use Spring Data JDBC to access a table that has a compound key, and although I can find lots of info on how Spring Data JPA handles this, the same doesn't seem to apply to Spring Data JDBC. Can anyone give a quick example of how you…
Ozzy
  • 71
  • 1
  • 2
7
votes
1 answer

SQLAlchemy: Querying compound primary key with `IN` operator

Assuming a table foo with compound primary key (a,b), How I can generate following sql query with SQLAlchemy (postgresql dialect)? SELECT * FROM foo WHERE (a,b) IN ((1,2), (2,3));
Taha Jahangir
  • 4,774
  • 2
  • 42
  • 49
7
votes
1 answer

How to define data.table keys for fastest aggregation using multiple keys

I am trying to better understand utilizing keyd data.tables. After reading the documentation I think I understand how to speed up subsetting when using one key. For example: DT = data.table(x=rep(c("ad","bd","cd"),each=3), y=c(1,3,6), v=1:9) Option…
dayne
  • 7,504
  • 6
  • 38
  • 56
6
votes
2 answers

Map with multiple keys in C++

I want to store data by both, their name and their index. In other words, I want to map string names to objects and also give them a custom order. What I came up with first is a std::vector of pairs of the string key and the object. The order was…
danijar
  • 32,406
  • 45
  • 166
  • 297
5
votes
2 answers

How to merge two dataframes using multiple columns as key?

Say I have the following dataframes: DF1 <- data.frame("A" = rep(c("A","B"), 18), "B" = rep(c("C","D","E"), 12), "NUM"= rep(rnorm(36,10,1)), "TEST" = rep(NA,36)) DF2 <- data.frame("A" =…
goldisfine
  • 4,742
  • 11
  • 59
  • 83
3
votes
1 answer

Clustering order does not work with compound partition key

With the following table definition: CREATE TABLE device_by_create_date ( year int, comm_nr text, created_at timestamp, PRIMARY KEY ((year, comm_nr), created_at) ) WITH CLUSTERING ORDER BY (created_at DESC) Comm_nr is a unique…
Alex Tbk
  • 2,042
  • 2
  • 20
  • 38
3
votes
1 answer

Compound key in Realm with lazy property

I found this great solution for using Realm with compound primary key in Swift: https://github.com/realm/realm-cocoa/issues/1192 public final class Card: Object { public dynamic var id = 0 { didSet { compoundKey =…
Marco
  • 1,057
  • 1
  • 19
  • 36
3
votes
1 answer

MySQL SELECT LAST_INSERT_ID() for compound key. Is it possible?

Can I get the LAST INSERT ID() for a compound key in MySQL?
atlacatl
1
2 3 4 5 6