A type of integrity constraint used in a RDBMS platform to ensure that a value in a column matches one of a range of key values from another table.

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27 views

Schema design - Reference slightly different data in different tables

I'm trying to design a schema for a MySQL database and got stuck on the following. My database stores documents which should have relations with blocks of content. create table document ( `id` ...
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20 views

Problems with foreign keys in a mysql database

I am trying to link both these tables with a foreign key. But I keep getting error message "ERROR 1452: Cannot add or update a child row: a foreign key constraint fails " the foreign key is pwalk_id ...
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1answer
23 views

Determining Homogeneity by Common Foreign Keys

I manage a MySQL database of ten or so tables. In higher code, I have a list of primary keys belonging to entries of some table A. These A entries have foreign keys to entries in another table B. The ...
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1answer
42 views

Conditionally join table

I'm new to database design and have designed a database that seems fine for the application but looks like it has a major red flag to me. I have a master table which is then joined to another table ...
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2answers
89 views

Altering table Foreign Keys produces an error (errno:150) (MySQL)

This is the first database I set up so I apologize if my problem is something obvious. I'm playing around with my table design and tried to create some link tables with FKs to avoid redundant data. ...
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1answer
22 views

Can triggers be used to implement automated polymorphic association?

(Apologies for any bad formatting or ignorance of common practices within this community; this is my first question here.) I'm attempting to (re)design a MySQL database for a personal social ...
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1answer
33 views

Sybase ASA: Saving and dropping all foreign keys and most Primary Keys for (Bulk) Insert

Background Information: I am trying to migrate from an ASA 12 Database, to a ASA 12 Database by using a Remote Server. I have to migrate a lot of Rows (not all), spread over a lot of tables (not ...
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1answer
42 views

Performance of checking for data in related tables

NB: this question is purely academic / to help improve my understanding of SQL Server performance. Given a master table which relates to one or more other tables, how would you determine the best ...
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2answers
339 views

multivalued weak key in ER database modeling

I was wondering since i didnt find out any clarification for this. I want to store movies that exist in different formats (dvd, bluray etc) and the price for each format differs from each other as ...
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1answer
29 views

Move Commonly-Repeated Fields into a new Table

I'm still at the design stage for a new system, and I've noticed there are several places where different types of object share similar fields. In this case, we have customers, offices, warehouses ...
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2answers
156 views

Usage of foreign key when the referenced table data will not change

I have to design a table where user has 10 fields and 6 are dropdown. Some are single selections and some multiple. Dropdown data is supposed to change very rarely. For e.g., the user is presented ...
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1answer
33 views

Batch converting indexes to keys [closed]

I have a legacy MS SQL Server database where all the primary and foreign keys were created as indexes. I am developing the new version of our software with Entity Frameworks, which I have learned ...
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1answer
331 views

MATCH FULL vs MATCH SIMPLE

I've noticed a MATCH SIMPLE or MATCH FULL option in phpPgAdmin, but I can't find a description in the docs. How do they function? The default is set to MATCH SIMPLE.
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21 views

Database relationship refresher

All, After several years of programming applications, I'm looking to refresh my understanding of databases. What I knew to begin with was fairly basic, and honestly, it's disappeared over time. I ...
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1answer
44 views

Query executes fast, but keeps the table locked for some time

Executing the following query is very fast (75ms), but removing the comment from the last row it becomes slow (2.5s), and the time increases exponentially with the number of rows in the table. It ...
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0answers
16 views

Redesign tables, multiple foreign key and related table to same table

Hello I have this database: Table Teams is used in each one table. Match table contains teamA and teamB and round contains team that win the SET and team that start the set. But I dont know how I ...
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1answer
84 views

Proper implementation of child (derived) table PK/FK during single and multiple inheritance hard coded generalization physical data model

Below is an image of hard coded generalization UML logical model of entities. I'd like to implement these classes as tables in a physical data model. Two derived classes/entities (Class2 and ...
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1answer
29 views

How to relate to information_schema

Is it possible to create a foreign key that relates to information_schema? For an application implementation, I would like to store extra column information in another table, but I want to ensure ...
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1answer
311 views

How to add FK on a column of composite type in PostgreSQL?

I have a table which contains a composite type and I am trying to connect a column of it to another table's PK. CREATE TABLE aaa (col1 SERIAL PRIMARY KEY); CREATE TYPE bbb AS (col2 INTEGER); CREATE ...
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38 views

Is it recommended to have redundant foreign key columns?

Imagine I have the models A, B, C e D, where A have many Bs, B have many Cs and C have manyDs: Without redundance A | id | ... | ------------ | ... | ... | B | id | a_id | ... | ...
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1answer
61 views

Error Creating Foreign Key in Oracle

I have 2 tables: PRODUCTS PREFIX SUFFIX ATTR1 ATTR2 ----------------------------------------------------- 001 AAA 50 100 001 BBB 20 300 010 ...
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1answer
99 views

MySQL Foreign Key Prevents Deleting Table — But Table is Empty

Why would dropping an empty table produce a foreign key error? In MySQL, I have a table with the following definition CREATE TABLE `enterprise_rma` ( `entity_id` int(10) unsigned NOT NULL ...
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1answer
63 views

More Details for MySQL's errorno:150

When MySQL can't create a table due to a foreign key constraint problem, it returns the following error Can't create table 'dbname.table_name' (errno: 150) Is there anyway to have MySQL tell you ...
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4answers
3k views

Recursive self joins

I have a comments table, which can be simplified down to this: comments ======= id user_id text parent_id where parent_id is nullable, but might be a key for its parent comment. Now, how can I ...
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1answer
173 views

Cannot add foreign key constraint while creating table

My Error Code is 1215 which finds problem with the foreign key constraint. I know all fields are the same data types. I can't see where the problem is. Any help would be much appreciated! Thanks! ...
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2answers
2k views

Foreign Key Constraint fails

I have the following tables: // Base Scans CREATE TABLE `basescans` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `name` VARCHAR(100) NULL DEFAULT NULL, `status_id` INT(10) UNSIGNED ...
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1answer
83 views

How to insert data into tables which reference each other?(MySQL)

I'm a student and right now I have a problem that I couldn't solve by myself(after searching on the Internet). I'm not going to give my «homework» because I want to learn what I'm doing but I will ...
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1answer
105 views

Slow delete caused by many foreign keys

My DB has about 90 tables. Most of the tables have an UpdatedBy and AddedBy column that have foreign keys pointing back to the user table. With even moderate amounts of data spread throughout the ...
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0answers
21 views

Approaching multiple values in same column

I'm developing an Android-application that scrapes the schedule for my university and presents it nicely since the current system is a nightmare. I'm processing a lot of data and it gets down to ...
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0answers
284 views

getting SQL Error (1452): Cannot add or update a child row: a foreign key constraint fails (Unknown error code)

I am getting error with MySQL NDB Cluster 7.3.5 as described below: I have two tables: -User Profiles -User Services User services is a child table which contains foreign key constraint ...
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1answer
35 views

Foreign key double inheritance SQLITE

I'm designing a domotic system database and I'm trying to figure out how to represent two foreign keys. This is the cardinality I want. Consider 1...N Areas (rooms, halls, kitchens, etc.): Area 1 - ...
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1answer
34 views

Save dataset within another table best practice

I want to save one dataset within another table, this dataset should be persistent. For example Table1: FIELDS (A,B,C) Table2: FIELDS (D, DuplicateTable1) I can think of 2 possiblities: Have ...
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0answers
30 views

Spotting foreign key relations in a database that doesn't define all relationships as constraints?

At work I use a rather old MS Access database which defines some relations between tables, but does not outright define all of them. If the database application used an ORM, I would think that this ...
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90 views

Crow Feet notation and identifying -vs- non-identifying relationships

Is it possible to distinguish between identifying and non-identifying relationships using the Crow Feet notation? Case in point: In table Book, part of the book's Primary Key is a FK to the Author ...
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1answer
35 views

Why use foreign keys if cascade action is not need?

I'm testing some queries with MySQL and tried to create two tables were there should be a reference between IDs. Something like: CREATE TABLE user ( id int(11) UNSIGNED AUTO_INCREMENT, name ...
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1answer
66 views

Implementing a simple ERD in MySQL: is the implementation below 100% compliant with the ERD?

ERD Consider the following ERD: Tables From it, I derived the following tables: Company ------------------ c_id c_name ------------------ CompanyEmail ------------------ c_id ...
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1answer
66 views

How to design to avoid two-way reference between two tables [duplicate]

I am having a problem with foreign keys between two tables. I am trying to model a relationship between members of a club and their relatives. This is a straightforward many-to-one relationship, with ...
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3answers
332 views

How to model a 1..1 Composition Relationship

We have a couple of entities/relationships of the following kind: Entity Event has a TimePoint The TimePoint contains time information about the event. It belongs to that event and cannot be used by ...
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2answers
82 views

Reasons for db2 foreign key error (-667) despite all rows appearing sane?

I have some csv formatted table dumps and loaded those into a new database with the tables defined by a DDL script from the source database (both acquired by somebody else so I cannot have a look at ...
2
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1answer
69 views

Relational modeled design to store versioned files

The scenario I have images in a database table and some of these need to be altered then re-saved(not overwriting the original) whilst providing a reference back to the original. I also save the ...
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1answer
103 views

How do I validate all my constraints in postgresql?

It seems like I have been bitten by the first bug described in the release notes of postgresql 9.3.4: http://www.postgresql.org/docs/devel/static/release-9-3-4.html I now have e.g. duplicate primary ...
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1answer
32 views

Insert / Edit Rows by Selecting FK row

When inserting or editing rows ("Edit Top 200 Rows") for a table with a FK constraint, can the editor be configured to select the foreign row, rather than me having to look up the FK?
2
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1answer
639 views

How can I create a Foreign Key to a Compound Primary Key with a single column?

I am working with a 'lookup' style table that is already in place, which has a compound primary key (not my design) in Microsoft SQL Server 2012. I want to add a foreign key to it in another table, ...
2
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1answer
720 views

Foreign key with multiple table options

I'm not sure if the title is very good, feel free to suggest a better one. People can "comment" on different objects of my site,similarly to StackExchange (for example they can comment on a Question, ...
2
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2answers
42 views

EAV-like table with both primary column pointing to the same foreign column

Background: I'm a programmer who, while had to work with simple databases several times, never had to work with complex ones. I.e. I'm proficient with basic stuff, but clueless about advanced features ...
1
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1answer
634 views

How to solve the error Msg 547, Level 16, State 0, Line 1 [closed]

Please suggest me how to solve the error How to solve the error Msg 547, Level 16, State 0, Line 1 The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "MyForeignKeyName". The ...
0
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1answer
104 views

Create table shows ERROR 1005(HY000) errno 150

i tried to create tables as per given in my textbook in MySQL server as follows: create table department (dept_name varchar(20), building varchar(15), budget numeric(12,2), ...
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0answers
28 views

Analyze a Database to Find Failed Foreign Key Constraints

I aggressively deleted a ton of data after using this query: SET FOREIGN_KEY_CHECKS = 0; Is there any easy way I can analyze the entire database to check to see if I have any hanging records that ...
2
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2answers
147 views

How to establish a Two-to-One table relationship (PK-FK-CK)?

My question is about DB design and its principles. I am working on a Python application where objects are mapped to database tables. I have Projects and People objects, mapped to their respective ...
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44 views

Why is adding a FK constraint slow in MySQL?

I'm doing some experimentation in MySQL 5.1.53 and I've run across a case that I just don't understand. CREATE TABLE A ( `pk` INT(11) NOT NULL, `fk` INT(11) NOT NULL, PRIMARY KEY `pk_A` ...