For this question, I am referring to the specific case where you have table T, it has primary key K, but K is a foreign key. Is this valid? And how would you write it in SQL99? All the other …
Tag: foreign-keys
How to make a foreign key on a different account
So I am currently using my account with username: ctxsys and a password In this account I have table named archiv11. In another account named d5a11 with a password I have a table called fileLocation …
cannot drop a foreign key in mySQL
It’s a common example between Persons and Orders. I just copied it from Internet as a test. CREATE TABLE Persons ( ID int NOT NULL, LastName varchar(255) NOT NULL, FirstName varchar(…
What’s the meaning of RESTRICT in Foreign Keys?
There is 4 cases: (For example I’m talking about ON DELETE) CASCADE: the referencing rows will be deleted automatically along with the referenced ones. SET NULL: the value of referencing record will be set to NULL automatically along with the referenced ones. NO ACTION: There will not be any change in the the referencing rows when the referenced ones are
error: there is no unique constraint matching given keys for referenced table “incident”
I know that this question has been already answered a million of times, but I couldn’t find any solution. Well I have these three tables on postgres sql. When I try to create the table incident_has_volunteer it throws the error there is no unique constraint matching given keys for referenced table “incident”. I tried to add on the third table
Sharing composite foreign key based on the same columns across multiple tables in MS SQL Server
I have database with multiple tables which contains information about different instruments (Currencies, Funds, Equities etc.). All instruments have Type and Id fields which represents unique key for …
SET CONSTRAINTS ALL DEFERRED not working as expected
In a PostgreSQL 9.3 database, if I define tables a and b as follows: And then do the following: It produces the error below. Why is SET CONSTRAINTS not having the desired effect? Answer Only DEFERRABLE constraints can be deferred. Let me suggest superior alternatives first: 1. INSERT in order Reverse the sequence of the INSERT statements and nothing needs
PostgreSQL Foreign Key syntax
I have 2 tables as you will see in my PosgreSQL code below. The first table students has 2 columns, one for student_name and the other student_id which is the Primary Key. In my second table called tests, this has 4 columns, one for subject_id, one for the subject_name, then one for a student with the highest score in a
Foreign Key constraints missing after phpmyadmin export
I create a table in mysql using the following script: When I export the created table from phpMyAdmin, I obtain the following script So the question are: where is my foreign key constraints? does KEY refer to FK? Seems that the two tables utente and attivita are no longer referenced in the new generated script. where am I doing wrong?
How to populate a table’s foreign keys from other tables
I’ve got the following tables, of which translation is empty and I’m trying to fill: The source data to fill translation is a temporary table that I’ve populated from an external CSV file: What I’d like to do is to fill translation with the values from tmp_table. The translated field can be copied directly, but I’m not quite sure how