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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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 ...
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60 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` ...
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42 views

Table Field to Reference Field in Other Tables

Suppose I want to map a set of input values to database table fields E.g. employeeFirstName --> emp.fName employeeLastName --> emp.lName ... --> ... In theory I can create a ...
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86 views

Error adding constraint foreign key to bridge table

Hi there I am fairly new to sql development. I am current following the head first into mysql book and is on chapter 6. On chapter 6 there is a table in third normal form but it does not contains the ...
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2answers
127 views

Multiple relationships between the same entities

Is there a name for when 2 entities can have multiple relationships between them?
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1answer
509 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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1answer
26 views

Good idea to include summary of frequently accessed data from another foreign-keyed table?

Sorry for poor title, I'll try to explain it in more detail here. I have an application that often gets a row from table A, then looks up a column from that in a foreign key mapping table (table B), ...
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89 views

Need advice on this EER Diagram

This db will work with a CakePhp app and need advice about design. Is it good idea to put orders on center or should I put clients on center? Clients has orders and an order record can only have one ...
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1answer
42 views

Table Design for user-specific and user-agnostic criteria

I want to design a table that is general enough to accommodate an increasing number of achievements as I come up with new accomplishments to reward. Initially, I thought to design the table as ...
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2answers
66 views

View for a MANY_MANY_MANY relationship

Let's say I have 3 main tables: category, tag, url category and tag have a MANY_MANY relationship (category_tag). tag and url have a MANY_MANY relationship (url_tag). I would like for a given ...
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1answer
1k views

Is there a way to skip errors in procedures and resuming procedure

When there is a unique key in a table (not PRIMARY KEY) and procedure is running, on duplicate key error the whole process will be halted. I want to resume on error and call the procedure again. ...
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2answers
771 views

Multiple child tables

I would like to know what is the best solution for making a parent table with multiple children? I have to make multiple children table. One for each profile. Is there a better idea than having 3 ...
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1answer
19 views

Foreign keys can't be added because they exist but they don't exist!

I have a conundrum. I am re-engineering a sqlserver 2005 database, and in the course of doing so have attempted to correct a simple lookup table flaw between tblUsers, tblUserRoles, and tblRoles ...
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1answer
17 views

alternative foreign key syntax

in mysql you can assign primary key constraint to a column using two different syntax: after the column is defined, separated by coma, optionally in a new line id int auto_increment, primary key(id) ...
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1answer
193 views

How to represent it with UNIQUE indexes and foreign keys?

"Group" is a group of pupils. "Topic" is a topic of lessons. To every group corresponds exactly one topic. (So there may be multiple groups per topic.) To a pupil corresponds multiple groups, but ...
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1answer
837 views

Cannot create FOREIGN KEY for a table [closed]

I'm not a professional DBA, I encountered a problem when I's attempting to create FOREIGN KEY for a specific table by the following SQL script (I'm using MySQL): ALTER TABLE mmy_answer ADD CONSTRAINT ...