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.
0
votes
1answer
95 views
Handling error of foreign key
How to set a FK value NULL upon receiving error for foreign key constraint?
Consider a simple table a
CREATE TABLE test
(
id int(11) NOT NULL AUTO_INCREMENT
ex_key int(11),
FOREIGN ...
0
votes
2answers
132 views
Merging Results while avoiding Key Constraint Error?
I have a table with a primary key which is two integer fields, each a foreign key to a different table. (Multi to Multi table)
In one of the foreign tables two rows are merged and this table is ...
0
votes
2answers
638 views
Query PostgreSQL 9.0 table on foreign key value?
Noob-type question:
Say I have two tables, candies and colors. The colors table holds just code/value pairs like 01 yellow, 02 blue, 03 green, etc. and is referenced in the candies table by code.
...
0
votes
2answers
22 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 ...
0
votes
1answer
14 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 ...
0
votes
1answer
24 views
Foreign key with multiple references
I have the following three tables in mysql database named "THE_COLLEGE"
mysql> desc students;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | ...
0
votes
0answers
69 views
How to represent class table inheritance (current DBMS-specific way please)?
I want to implement class either-or table inheritance (Account, CatAccountDetails, DogAccountDetails) in SQL Server.
I found a recommendation for MySQL here (How do I map an IS-A relationship into a ...
0
votes
1answer
79 views
Modify MySQL foreign key related column without dropping foreign key relation
I need to modify a foreign key related column. When I tried to alter it I got "Error on rename of 'x' to 'y' (errno: 150)" error. So I googled and found foreign key relation is the 'villain'. I ...
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votes
0answers
133 views
Consequences of multiple FK's from same column to multiple tables
I know it's possible to create multiple FK's to different tables using the same column, other than the performance hit caused by having a FK, are there any negative consequences of doing so?
...
0
votes
2answers
58 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 ...
0
votes
1answer
107 views
Pitfalls of creating a foreign key constraint on a system table?
I have a number of tables which hold metadata about the tables and packages in the system. This is intended to be a resource for analysts and documentation so it is not used to create data.
One of ...
0
votes
0answers
40 views
How can I make MySQL rework its foreign keys?
I somehow tricked MySQL into believing I have a foreign key that does not exist.
I had a table with both an Id column and a Number column. I wanted to merge the two, so I cleared the few tables ...
0
votes
1answer
293 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.
...
0
votes
1answer
32 views
Refer to a table with all rows or to the table which restricts allowed rows?
There are some discounts:
CREATE TABLE `discounts` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`value` decimal(4,2) NOT NULL,
`titleru` text COLLATE utf8_bin NOT NULL,
`titlehe` text ...
-1
votes
2answers
466 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 ...
