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).

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Composite Foreign key to single primary key [duplicate]

How do I create a composite foreign key to a table with a single primary key? For example suppose I have the following tables: CREATE TABLE Branches ( BranchId UniqueIdentifier DEFAULT ...
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32 views

Re-posting schema

I'm building a social network very similar to Twitter, in which users can see a feed with content posted by users they follow. Users can like and re-post (i.e. "Retweet") posts. Re-posted content ...
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PostgreSQL: schema diff/patch tool [closed]

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 ...
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How to determine a schema version at runtime

Is there a portable way or best practice to access a version number for a schema at runtime? Rationale: you have multiple systems (development, QA, etc.) where you push schema changes from one system ...
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30 views

Rescue truncated data from incorrect column type

I have mistakenly inserted a variable 18-20 digit variable into an unsigned INT() column. The data has been truncated to the max 32bit length so all my data is displayed as "4294967295" Is there ...
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27 views

Which foreign keys do I use if they are repeated

I have the following two tables company_relationships |ID|Company_ID|Affiliate_ID|<Relationship Info>| +--+----------+------------+-------------------+ jobs |ID|Company_ID|<Job Info>| ...
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69 views

Entity Schema Design

I'm working on an application that has an "entities" system (built before my time) that models users, customers, contractors, vendors, etc. These are all types of people, but have different needs in ...
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29 views

Working out validity of table relationship

Question Background: In a quest to improve my skill set with TSQL programming I'm designing a 'simple' database schema for a zoo. In all I currently have 4 tables but am having an issue working out ...
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What is the difference between logical schema and physical schema?

While going through Database architecture I came across Schema's . I am very much confused with: Logical schema Physical schema How these two schema exist in the Database? How can these be ...
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How to store highly configurable relationships based on multiple conditions

I'm trying to devise a schema that needs to be extremely configurable when necessary, but also minimal wherever possible. There is a large number of condition types that would lead to a number of ...
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54 views

to pivot or not to pivot - schema design question [closed]

I am implementing something similar to this schema http://www.databaseanswers.org/data_models/event_reservations/index.htm It occurs to me that the pivot table for Customer_Bookings would just keep ...
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28 views

Ensuring that 1 row has 5 specific records referencing it

Context: a TEST has many CASEs. Typical. However, the catch is that a TEST instance must have exactly 5 instances of CASE (1 to 5). I could do something like this: create table TEST ( ID ...
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30 views

Database & Structure for SaaS reporting software

I'm building a SaaS application to allow users to upload data and perform reporting and analytics on it. The reporting and analytics would be quite simple like grouping and aggregating. This has ...
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11k views

How can extract the table schema from just the .frm file?

I have extracted the data directory of mysql from a backup and need to get the schema from an old table, however it's a backup from a different machine. I have read a fair number of tutorials today ...
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1answer
731 views

Updating mysql trigger via information_schema — access denied?

I have some wrong "definer"s for some triggers in MySQL (actually MariaDB). I figured the easiest way of correcting them would be some version of: use information_schema; update triggers set ...
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2answers
85 views

Unique column values between tables

I'm keeping track of teams and their members. Each team has one leader, one contact person, and any number of players, and each of them has a unique email address. The problem is that one physical ...
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1answer
1k 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 ...
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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 ...
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1answer
437 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 ...
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1answer
40 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 ...
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303 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 ...
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1answer
155 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 ...
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173 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 ...
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3answers
560 views

What is the optimal solution for converting a database schema?

I actually want to get rid of the existing constraints in the database which I know sounds crazy but we are upgrading our application to a new framework which relies on the foreign key constraint ...
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1answer
78 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 ...
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1answer
601 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 ...
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1answer
546 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 ...
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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 ...
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which role-permission database design?

I want to manage roles and permissions. Most of designs on web look like this tables: Users Roles UserRoles Permissions RolePermissions Here, what is permissions? I am thinking for such a design ...
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102 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 ...
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83 views

Need help with data model

Schema does not list all fields, but only the relevant ones User adds credits/funds to his account using paypal or Internet Banking (which has to be verified manually, and approved, so the 'status' ...
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1answer
91 views

Is there a way to create a re-usable base table definition in InfoSphere Data Architect?

Our company has chose to use IBM's InfoSphere Data Architect (IDA) for data architecting regarding our data warehouse and data marts. The data architects originally designed several "re-usable" ...
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2answers
76 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 ...
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2answers
50 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 ...
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62 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 | ...
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125 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 ...
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67 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 ...
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2answers
2k views

Import Oracle schema data without losing modifications of stored procedures

I have this scenario: One huge (thousands of tables), complex production database, Oracle 8 One huge (thousands of tables), complex development database, Oracle 9 ( same structure as production ) ...
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55 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 ...
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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 ...
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2answers
70 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 ...
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1answer
33 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 ...
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212 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 ...
2
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2answers
64 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 ...
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2answers
994 views

How can I organize my tables?

My database contains more than 200 tables. When I want to modify or insert a table, I find it difficult to find it among all those tables. Is there any way to collect related tables in a folder ...
2
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1answer
504 views

date dimension OLAP cube design

I have a sales reporting system with incoming data like this date,editionID,outletId,Measure1,Measure2 2013-01-01,2,532,11,24 etc... I am new to designing data cubes (for the pentaho BI suite) and ...
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124 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 ...
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1answer
62 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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92 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. ...
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165 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', ...