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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Recreate all foreign keys in all tables as deferrable (batch)

I want to make all foreign keys in my database deferrable. But there is no possibility to alter an existing constraint. So I need to drop and add again each foreign key. How to do it automatically?
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82 views

Discover missing foreign keys and/or indexes

We have a pretty big database (around 700GB of data), which has been inherited to us, and has had several DBAs. With time we've realized that there are several missing foreign keys and indexes. I'd ...
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1answer
106 views

Oracle: Traversing a graph of my foreign keys?

Given a table, what is a query that will show foreign key constrains, both immediate and nested? I.e. if T2 has an FK on T1, and T3 has an FK on T2, I would like to show T1 -> T2 -> T3.
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2k views

adding autoincrement to id already part of foreign key

I would like to add the autoincrement property for all my table's columns named id in a schema. However, most of them are part of a foreign key constraint. Is there any other way to do it without ...
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1answer
38 views

is there some way to give me the order in which inserts should be made so all FK constraint are met? [closed]

I have a mysql 5.6 schema with about 60 tables. I need to write some code (not sure if it will be Sql or java) to populate the data. The schema has lots of FK etc. Is there some good way (I am ...
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1answer
103 views

“Transitive” keys

I have a central table, A, which will have a key that I'll call A_ID. Now, I have a table B in a "one to many" relationship with A (many B's map to one A). Each link will, of course, have a link ...
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1answer
70 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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1answer
921 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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1k views

Can a foreign key have a default value equal to 0?

I have a column whose default value is 0 .Can I make that column as foreign_key
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7k views

“Cannot add or update a child row” when deleting a record?

I have the two following tables: survey_main ---------- id name answers_main -------------- id survey_id I have the following foreign key constraint on the answers_main table: CONSTRAINT `...
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2answers
181 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
2k views

Foreign Key to Multicolumn Primary Key?

I have three connected table in my design. Basic logic is when a category deleted, also delete records in category_product table which has deleted category's id in its cat_id column. But when I tried ...
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4k views

Getting the data from a foreign key table

I have a table that relates a user to client using both their table id's UsersClients Table --------------------- | userid | clientid | --------------------- | 2 | 32 | | 3 ...
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282 views

Use single table with foreign key or two twin tables for text entries?

I have a table answers that has several columns including the content iself such as ID | q_id | list_id | user_module_id | content | updated_timestamp The content column is a varchar since we want ...
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2answers
1k views

Naming foreign key columns

Now I hear that the best practice for naming foreign key columns is the name of the table and field (and maybe the function if there are multiple foreign keys to the same table), for example, a ...
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1answer
11k views

To drop a table, do I have to drop all foreign key constraints or can I just NOCHECK them?

I know you cannot drop a table that has active foreign key constraints. So I was wondering is it safe to: ALTER TABLE myTable NOCHECK CONSTRAINT all DROP TABLE myTable Rather than dropping the ...
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2answers
13k 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
49 views

Distinguish between unknown and non-present foreign keys

I'm in the situation of importing data from multiple other applications. The data is stored in multiple tables that contain foreign keys. Some of these applications don't provide all the needed data ...
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1answer
34 views

Tricky condition for PostgreSQL UPDATE query

I need help with a PostgreSQL query. I have a Django app + pg backend, where users post interesting URLs (or links) and can then comment under such links (called replies). There are two pg tables to ...
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1answer
116 views

SQL Server Management Studio: The columns in table do not match an existing primary key or unique constraint

I have two tables: Students and Courses. I want to set a foreign key in the Students table from the couseId column to the courseId column in the Courses table. I have set primary keys to both ...
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1answer
56 views

SQL Query; Admin Log System; Foreign Keys; Retriving multiple rows form different tables at once

Table A (users) id | name | ip 52433 Yashas 1.1.1.1 512 Admin 5.6.7.8 Table B (admin_record) id | admin | time | date | reason | action 52433 512 2312352 ...
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1answer
234 views

“Merge” two rows in a Postgres table, with foreign keys

I am keeping a database of books I've read, using the following two tables in PostgreSQL: CREATE TABLE authors ( id SERIAL PRIMARY KEY, name text ); CREATE TABLE books ( id SERIAL ...
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1answer
40 views

What is the best approach to find all fields that has (Foreign Key and Primary Key) constraints in a Mysql database?

I have a mysql database that has 250 tables. I would like to run a query to retrieve: tableName ; FieldName ; ConstaintName (Primary or foreign key). I could use information_schema....
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1answer
271 views

MySQL Dump Restoration when FOREIGN_KEY_CHECKS=0

I currently use a SaaS DBMS. Backups of my database are provided to me in the form of a MySQL dump, and I noticed that FOREIGN_KEY_CHECKS=0. I am annoyed by this because it appears that this dump is ...
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1answer
84 views

How to reference a UNIQUE KEY CONSTRAINT in parent table as a foreign key in child table?

I have created two tables, the parent in this case being "department" and "employee" being child. CREATE TABLE department ( department_id NUMBER(4) CONSTRAINT department_id_not_null NOT NULL, ...
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1answer
91 views

Should child comment be treated as separate table?

I'm building a commenting system, currently my table indicates which comment is child with parent id in 1 table, I would like to know what is the best way of doing this? Current Table Scheme (1 Table)...
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1answer
134 views

Foreign key constraints failure when cross updating between two databases

I have two databases (com and usa) with a table with the following schema: Create Table: CREATE TABLE `eav_attribute` ( `attribute_id` smallint(5) unsigned NOT NULL AUTO_INCREMENT COMMENT '...
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1answer
70 views

Adding restaurants in database

I wanna store some vendors (like McDonald ,etc) and it's branches in a table. a vendor may,or may not have branches. I have created two tables: 1- A vendors table which have name,logo, etc. 2-A ...
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1answer
251 views

Foreign key default value

I have a master table and another table with foreign key. I can easily add data to master table. But whenever I want to add data to the connected table, I get a message saying Foreign key doesn't have ...
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1answer
142 views

Rename PK column names when they are FK in another tables

I need to change the names on PK columns and that has relations with another tables meaning they are FK also so this is what I am doing: SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0; SET @...
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1answer
142 views

How to get a surrogate key value in order to put a foreign key in and create relationship?

I am trying to create two relationships between three tables, using foreign keys with values of primary keys, which are surrogate keys. But I don't understand how to enter the right value in the ...
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1answer
264 views

How to write a query which recursively returns all foreign key references to a column?

I need to obtain a list of foreign keys which refer to a given column, as well as all foreign keys which refer to those keys, and so on. Order does not matter. I have SELECT s.name, t.name, ...
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2answers
259 views

Mysql might have too many indexes

I am using the php framework Laravel for my application, together with mysql 5.6, in order to have full-text search with innoBD. But I am not sure if I have too many indexes. My application allows ...
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1answer
155 views

Transactional Replication - Replication Order of Related Tables

** This was previously asked on Stackoverflow - I removed it from there and recreated here ** I have an issue with SQL Server Transactional Replication. My topology is as follows (and this cannot be ...
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1answer
2k views

#1025 - Error on rename of table errno: 150 : Table was deleted while tried to assign foreign key

When I tried to assign foreign key to a table named mydb.table1 it was deleted from my database, I could not understand the reason and tried to move on. For this tried to create same table with create ...
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1answer
345 views

How to insert values into a junction table?

I add values into my two tables using the code below, but I also have a junction table called book_main_cover and I want to add data into this table to make a connection between book_id and ...
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1answer
30 views

Relation between tables [closed]

This question may be too easy to ask, but I can't understand how to do it. I am new in SQL. I have two tables. Table I book_id (AI & Primary Key) book_name book_year Table ...
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1answer
467 views

ON DELETE CASCADE not working

Trying to implement a simple user follower system in MySQL, using a junction table: CREATE TABLE users ( id int NOT NULL AUTO_INCREMENT, email varchar(255) NOT NULL, username varchar(25) ...
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1answer
76 views

MySQL: Is there a way to update a field so that all foreign key related fields are updated as well?

I'm assuming the answer to this question is yes but it is hard to Google this type of question and not get overly ambiguous results. I am working with a database that was dumped from a Magento ...
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1answer
40 views

Help on MySQL joins

I'm building a system to monitor currency prices. Part of my database structure looks like this: My system is trying to pull the api ticker for each exchange with this query: SELECT distinct E....
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2answers
88 views

Suggestion for Tooth Chart Data Structure

Hello I'm not sure if this is an OK question here but here goes, I'm quite confused on how am I going to make the data structure of my tooth chart database. I had first this thought of making a data ...
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1answer
626 views

Adding foreign keys constraint on databases used

We have a server with about 20 databases, all duplicates of the same original db, and we just noticed the original is missing all the foreign keys constraint for some unknown reason. So of course all ...
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1answer
30 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
153 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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1answer
10k 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
160 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
265 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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2answers
91 views

MySQL foreign key error

I need to update rows in a child table,but I am getting following error while I run the code, Company Table CREATE TABLE `company` ( `Company_id` int(11) NOT NULL AUTO_INCREMENT, `Company_name` ...
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1answer
282 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
3k views

Allow self-referential foreign keys to be null from an alter-table

I am trying to establish a hierarchical relationship between rows in an existing table. There are two fields of interest: a not-nullable primary key field id, and a second nullable field parentId. ...