A schema of a database system is its structure described in a formal language supported by the database management system (DBMS) and refers to the organization of data to create a blueprint of how a database will be constructed (divided into database tables).

learn more… | top users | synonyms

1
vote
1answer
21 views

PostgreSQL complaining about shared memory, but shared memory seems to be OK

I've been performing kind of intensive schema dropping and creating over a PostgreSQL server, but now complains..: WARNING: out of shared memory ERROR: out of shared memory HINT: You might need to ...
0
votes
0answers
8 views

CROSS JOIN and updatable model design for Ruby on Rails [duplicate]

I am trying to build the multi-level model in rub on rails to allow the following to happen: When a user creates a campaign they will select some categories and some metros from tables Category and ...
0
votes
1answer
10 views

Schema for a reservation system

I'm working on a reservation system schema and have some problems defining availability of resources. I searched for similar question here and on Google but still don't have clear understanding My ...
1
vote
1answer
20 views

What are some databases that are schema-full but not relational

What are some databases/datastores that are schema-full, but not relational? In other word I'm after some NoSql databases that are not schema-less. By schema-full I mean that, like in a traditional ...
1
vote
1answer
57 views

Friendship and Messages in a MySQL table relational schema problem (concerning big data manipulation)

Before you start suggesting this question for duplicate read it, I have searched and i haven't found any proper solution. So, i'm building a social networking site (I know that you are laughing ...
0
votes
0answers
50 views

Changing Schema ownership and side effects

I am trying to understand why changing schema ownership is causing permissions to be revoked. I am having a hard time understanding schema ownership change. Here are the steps I have taken in ...
1
vote
1answer
20 views

MySQL Junction Table as Foreign Key?

I have several tables: company, customer, company_has_customer, and transaction. company_has_customer is a many-to-many junction table using the PKs of company and customer as its PK. In almost all ...
0
votes
1answer
42 views

DB2 - how to safely blow away database on linux?

I'm using (I believe) 10.1.2, on CentOS 6.5 (for sure). The underlying problem I have is that the database upgrade package prepared in house isn't working for me, in at least the sense that the ...
1
vote
1answer
24 views

Permission for sequence in another schema

Postgres 9.3 Debian 7.0 I created a specific schema for a specific user and created a view in this schema for this user, so it's the only table he knows that exists. The problem is that this same ...
1
vote
1answer
49 views

Handling user logins while using a multiple schema design to support multi-tenancy

I'm creating a web application (in PHP and PostreSQL) that will be used by organisations and their staff and I want to use multiple schemas to support multi-tenancy. There will be one database and I ...
1
vote
3answers
59 views

Query to compare the structure of two tables in MySQL

To automate the backup process of one of my MySQL databases, I would like to compare the structure of two tables (current version vs old version). Can you think of a query that can compare two ...
1
vote
1answer
91 views

Schema unusable after deleting another database

I just get a problem with a customer's SQLServer. I'm reading articles related to schema, owners and permissions, but I can't get it out. I have two DB : DB1 and DB2. I have a schema, which has the ...
0
votes
1answer
56 views

Convert multiple databases into schemas SQL Server

Due to a high amount of databases being created on my project and the rising cost per databases I had the following question: Is there a way to convert multiple databases in SQL Server into one ...
2
votes
2answers
32 views

Schema for storing historical data on shared identifiers

When user account is assigned an IP address, I create a table entry for the account/IP mapping. This data in the table is updated every 5 minutes. Right now I'm only keeping real-time data but I need ...
5
votes
2answers
41 views

How to enforce the structural constraints of rectangularly arrayed data?

(I'm particularly interested in answers that view the question below as a special case of the question: how should a RDBMS enforce structural constraints that are more specific than "one-to-many" and ...
1
vote
1answer
51 views

Does a Key-Value type table still needs a auto increment key?

Suppose that I have a very simple table to store variable-like data, like this: +-----------+-----------------+ | key | value | +-----------+-----------------+ | site_url | ...
0
votes
1answer
47 views

Schema for multi-account database

I'm building an app which will have accounts for organisations leading to organisation.myapp.com subdomains for their account access. I'm putting together the schema for it and I have a few ...
0
votes
1answer
38 views

modelling warehouse picking

What's the best way to approach modelling a warehouse picking system? To be precise, customers place orders which are processed by warehouse staff. A simple products and orders database isn't an ...
2
votes
0answers
53 views

Which is the better schema design for a voting system?

Imagine a q/a site or forum similar to stackoverflow. I'm trying to determine which of these two methods would be the better design for a voting system: (note: I would also like to keep record of all ...
1
vote
0answers
20 views

Can I include extra columns in a m->m mapping table? [duplicate]

I guess this is sort of an odd question, but consider this scenario. table classes (id_pk) table students (id_pk) table students_classes_map (students_id_fk_pk, classes_id_fk_pk, finalExamScore ...
2
votes
1answer
53 views

select query on unique column AND alternate column of “aliases”

I have a MySQL table (~10,000 rows) with a pk id (int) column and a name (varchar) column (as well as a few other unimportant columns for this question). The name column contains unique values that ...
1
vote
1answer
73 views

PostgreSQL: schema diff/patch tool

Consider the following setting: A production DB A dev db, on which schema changes are made to enable new features When the development of a new feature is complete, I have to manually update the ...
1
vote
2answers
52 views

Why WordPress use a column prefix? [closed]

I'm trying to learn some basic database design through open source projects. And look into the WordPress database schema, the posts table for example, you'll find something like this post_author ...
1
vote
1answer
21 views

How to put this particular constraint on this link table in MySQL? [duplicate]

I have the following three tables in MySQL: Store, Groups, StoreGroup. A store can belong to several groups. StoreGroup is the link table that records the groups a store belongs to. The Groups table ...
5
votes
2answers
93 views

Creating a table with many optional fields

I am a developer (student) looking for some advice on what best approach should I follow while creating a table to model an entity that has a number of optional fields. There exists a need to model ...
1
vote
2answers
27 views

What's the best design for a logical structure that contains different properties of various types for different entity categories? (MySQL or NoSQL)

I'm designing a MySQL database that needs to contain a list of products. Those products, based on their category, will need to have a list of various properties. Let's say all products in category ...
0
votes
2answers
69 views

How to count all relationships in a database?

I am developing a web application, which stores data in a Microsoft SQL Server database. My project manager has to deliver a report to non-tecnhical higher-ups, and thinks that it will read impressive ...
1
vote
1answer
45 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` ...
0
votes
1answer
33 views

Trigger on a Schema

Is it possible to create a Trigger on a Schema? I have to audit the changes on my tables. But I have a lot of tables and I don't one to create a trigger on them one by one. --Database level trigger. ...
0
votes
2answers
73 views

How to change schema so that account_id reference is unique among 3 tables

Original image: Updated to have more-correct terminology and an 'is_debit' column: I am designing a (PostgreSQL) schema for a lottery website that uses double-entry accounting. 'jackpots', ...
0
votes
0answers
18 views

Export sql server table connections schema

i am using RazorSQL to connect to a Microsoft SQL Server database. I am looking for a way to visualize the tables connections schema. Do you have any idea how I can export such a view?
0
votes
0answers
52 views

Cassandra: unstructured document storage?

I'm fairly new to NoSQL, but fairly experienced with SQL-based relational databases. We are evaluating Cassandra for one of our applications. I've seen where Cassandra is claimed to be able to store ...
0
votes
0answers
8 views

Managing schema migrations in Mondrian

Managing schema changes across dev, stg, prd is something we do well in our home-grown solution today. Specifically, at least one downstream team consumes our star schema. They're considering ...
0
votes
1answer
106 views

Postgres 9.3 changes the standard_conforming_strings value

I'm migrating a legacy application's database from Postgres 8.1 to Postgres 9.3 In order to avoid compatibility issues, I'd like to keep the standard_conforming_strings parameter to it's default ...
0
votes
0answers
70 views

How to share Users table between Clients and Customers?

I have a rental system where the system admin can add clients and their users. Each client's user can manage products, categories, orders etc., as well as their own customers. However, while ...
0
votes
3answers
67 views

What is the EXPORT privilege on ORACLE

I have created a user say A. I want to export some of my schemas using A user. For example, I have B and C users. I want to export B schemas using A user. Which grant do I have to use? I am using ...
0
votes
2answers
28 views

Design for table with multiple links to other table

I am designing a database to keep track of our network equipment. My db has 2 tables: sites & circuits (circuit = cable) & (site = property location) Each circuit runs between two sites, so ...
1
vote
0answers
26 views

To implement a facade DB table or not? [pics]

Does it make sense to normalize a schema with tables that only serve the purpose of logically separating parts of a system? Below are 2 example schema with what I am talking about. (sorry about the ...
1
vote
1answer
69 views

Data modeling with many attributes where few apply to each record [closed]

I'm pretty new to data modeling, so please excuse me if I've missed something obvious. I'm trying to decide on a schema (or possibly a DBMS) to work with some data where there are quite a few possible ...
0
votes
2answers
59 views

Transfer all tables from a schema to other schema

I have two schema. Schema1 and Schema2 How would I transfer all the tables from schema1 to schema2?
-1
votes
2answers
25 views

query multiple unrelated tables

Just learning mysql and db so guess this is a general schema design question. Say i have 10 different types of widgets and each widget transaction has a date, amount and 8 other unique columns to that ...
2
votes
2answers
49 views

Is there a good way to select a row where the key represents the lower bound of a range?

I am designing some tables and a number of the tables have as the key a lower and upper bound which never overlap. I want to query by a value that can fall withing any of those ranges. If I keep both ...
2
votes
1answer
101 views

SQL Server many-to-many relationship, row reuse?

Below is your typical many-to-many relationship. Pretend there are 2 tasks that have the exact same Tags. because of foreign key/primary key relationship constraints, there is no way for the rows in ...
0
votes
1answer
105 views

Duplicate Relationships in Rails/MySQL Healthcare Application

Overview of the Application I am building a Ruby on Rails application to organize medications, using MySQL. The goal of this application is to provide dosage specific treatment recommendations, and ...
1
vote
1answer
54 views

What will GRANT <privilege> ON ALL TABLES IN SCHEMA <scheme> TO <role> do?

It seems obvious that PostgreSQL will GRANT some privileges ON ALL TABLES IN some schema TO some role when I'll command. But, will it make it permanent for the schema that on all tables within it, ...
1
vote
0answers
110 views

How do you think in NoSQL? [closed]

I'm from the pre-nosql era and am rather comfortable with SQL. However, I cringe whenever someone suggests using a NoSQL database for the "upcoming" project. There are some major problems that I'm ...
0
votes
1answer
63 views

Database design Problem for the web-app

Hello I am in a problem of designing a web-app database schema. Suppose I have 10 shops and every shop gives deals on every different day Sunday, Monday and so on and for limited time period like ...
2
votes
1answer
70 views

Review database schema / thought process

Please review my thoughts below. It is written in an authoritative style because it is the most succinct, not because I am competent. Please poke as many holes as possible. I am trying to create a ...
0
votes
1answer
70 views

Need some expert eyes to look at my schema

I am trying to make an online site for local movies. Will be written in PHP and will be using MySQL as the database. What I want is to create a mini IMDB type site, with movies, people(casts/crew), ...
1
vote
0answers
201 views

Neo4j vs mongodb [closed]

I want to store data of parents,teachers,students,subjects and the respective marks. All these entities are highly interlinked. Different schools have different type of data and each student will have ...