relational-database

phpMyAdmin - Error: relational features are disabled

由 拈花ヽ惹草 提交于 2019-12-03 07:28:01
When I want to create a relation between two tables in designer mode with phpMyAdmin 4.3.8, it gives me an error saying: Error: relational features are disabled! When I try it with 4.1.4, it works just fine. I can't seem to find where I should change the settings to be able to create relations in designer mode. Any idea? Thanks in advance! Convert your table/db engine to InnoDB using ALTER TABLE table_name ENGINE=InnoDB; Change your table engin to InnoDB using: ALTER TABLE your table name ENGINE=InnoDB I had the same issue, it was because I didn't have a database on the mysql server for

Can one make a relational database using MongoDB?

由 坚强是说给别人听的谎言 提交于 2019-12-03 06:44:09
问题 I am going to make a student management system using MongoDB. I will have one table for students and another for attendance records. Can I have a key in the attendance table to reach the students table, as pictured below? How? 回答1: The idea behind MongoDB is to eliminate (or at least minimize) relational data. Have you considered just embedding the attendance data directly into each student record? This is actually the preferred design pattern for MongoDB and can result in much better

Searching by related fields in django admin

由 ぃ、小莉子 提交于 2019-12-03 05:54:59
问题 I've been looking at the docs for search_fields in django admin in the attempt to allow searching of related fields. So, here are some of my models. # models.py class Team(models.Model): name = models.CharField(max_length=255) class AgeGroup(models.Model): group = models.CharField(max_length=255) class Runner(models.Model): """ Model for the runner holding a course record. """ name = models.CharField(max_length=100) agegroup = models.ForeignKey(AgeGroup) team = models.ForeignKey(Team, blank

Relational vs Non-Relational Data Modeling - what's the difference

由 谁说我不能喝 提交于 2019-12-03 05:46:43
问题 I'm new to databases and I've never worked with any RDBMS. However I get the basic idea of relational databases. At least I think I do ;-) Let's say I have a user database with the following properties for each user: user id name zip city In a relational database I would for example model it in a table called user user id name location_id and have a second table called location location id zip city And location_id is a foreign key (reference) to an entry in the location table. If I understand

How to empty my destination table before inserting new records in SSIS?

由 隐身守侯 提交于 2019-12-03 05:37:11
I use SSIS to generate and transform new data for later use in a new system. I have a problem every time I run my SSIS Package, it keeps inserting new records to my destination tables. How can I empty my destination table (/OLE DB Destination) first and then inserting the newly generated records? Currently the workaround for this problem is performing a delete from DestTable before running my package. Put your delete statement in an Execute SQL Task . Then make it the first component of your flow. The component looks something like this: Create an Execute SQL task. Have it run first. For the

Data Modeling: Supertype / Subtype

由 旧城冷巷雨未停 提交于 2019-12-03 05:25:39
问题 Looking to figure out the proper way to model the below requirements. There are 3 types of “parties” to be concerned with, a Fan, a Band, and a BandMember. That BandMember will always be associated with a Band and can also be a Fan of any band. There are common attributes between a Fan, a Band, and a BandMember, but each of these 3 will also have their own unique attributes. A Fan can be a fan of of any Band or none at all This is a small part of a bigger thought but it is creating confusion

best way to store 1:1 user relationships in relational database

由 只谈情不闲聊 提交于 2019-12-03 05:13:36
问题 What is the best way to store user relationships, e.g. friendships, that must be bidirectional (you're my friend, thus I'm your friend) in a rel. database, e.g. MYSql? I can think of two ways: Everytime a user friends another user, I'd add two rows to a database, row A consisting of the user id of the innitiating user followed by the UID of the accepting user in the next column. Row B would be the reverse. You'd only add one row, UID(initiating user) followed by UID(accepting user); and then

Representing Sparse Data in PostgreSQL

由 人走茶凉 提交于 2019-12-03 05:04:33
问题 What's the best way to represent a sparse data matrix in PostgreSQL? The two obvious methods I see are: Store data in a single a table with a separate column for every conceivable feature (potentially millions), but with a default value of NULL for unused features. This is conceptually very simple, but I know that with most RDMS implementations, that this is typically very inefficient, since the NULL values ususually takes up some space. However, I read an article (can't find its link

Soft Delete vs. DB Archive

由 佐手、 提交于 2019-12-03 04:05:24
Suggested Reading Similar: Are soft deletes a good idea? Good Article: http://weblogs.asp.net/fbouma/archive/2009/02/19/soft-deletes-are-bad-m-kay.aspx How I ended up here I strongly belive that when making software, anything done up front to minimize work later on pays off in truck loads. As such, I am trying to make sure when approaching my database schema and maintenance that it can maintain relational integrity while not being archaic or overly complex. This resulted in a sort of shudder when looking at the typical delete approach, CASCADE. Yikes, a little over the top for my current

Safe modelling of relational data in Haskell

由 南楼画角 提交于 2019-12-03 03:38:08
问题 I find it very common to want to model relational data in my functional programs. For example, when developing a web-site I may want to have the following data structure to store info about my users: data User = User { name :: String , birthDate :: Date } Next, I want to store data about the messages users post on my site: data Message = Message { user :: User , timestamp :: Date , content :: String } There are multiple problems associated with this data structure: We don't have any way of
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