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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Single-Table vs. Multi-Table design

I'm trying to come up with a database schema which is going to be used for a social network similar to that of Facebook. Now for posts I have two schemas in mind which are as follows: Single-Table ...
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39 views

Default schema is ignored on SELECT

According to my understanding, a default schema should apply when issuing SQL statements on tables using unqualified table names. My problem is that the following statement fails, because the table ...
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52 views

Apply operation on all schemas

I have an Oracle instance, with several schemas (all starting with the same prefix). PATT_A PATT_B PATT_C ... All of them have the same table, and I'd like to update all of them in one shot (with ...
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Best Approach to Migrating Oracle to MySQL - Run on EC2 in AWS

I'm trying to migrate an Oracle schema as well as all of the data within the DB to a MySQL database. I want to then make an EC2 app on AWS to kick off whatever I've written for this. Are there any ...
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836 views

Is an ER diagram an example of a conceptual, logical or physical schema?

I have been reading databases, and I clearly understand the difference between a conceptual, logical and physical schema. An ER diagram is an example of which of these schema's?
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Is it a good idea to add a reserved field to a large MySQL table?

As you may know adding a new column to a MySQL table with millions of records is hard and in some cases impossible. Is it a good idea to add a text column to each table (say, meta) to save some ...
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368 views

Is there a way to replicate certain part of collection in Mongodb

Is there away to stream certain part of collection in MongoDB or TokuMX from master server to another server? I need to duplicate only certain collection Or if it isn't possible, are there any other ...
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32 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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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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165 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), ...
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198 views

Unable to check is schema is present first

I've created a SQL script that will release a process to numerous SQL Server instances so I want to check if a paticular schema is present before creating the schema. I'm using the below and it ...
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1k views

Multi-Tenant (SaaS) Database Schema with Sharing

Guys I just need your opinion which is the best approach to design a schema of a database for a SaaS application. I want it all on a single database, At first I think I can simply put a context_id ...
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103 views

is there a recommended way to update many postgres schemes

I have a database in postgres which has 15 schemes, the schemes are identical with the same tables, views and functions. the system uses one scheme at a time, as if they were separate databases. So ...
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2k views

Granting permissions only on a set list of objects

I have a SQL Server 2005 database with a large number of tables in the dbo schema. I now created a new schema (call it myschema) that only has three table-valued functions and two stored procedures in ...
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6k views

SQL Server Database Diagram in SQL Management Studio creating multiple schemas

I'm using a multiple schema approach (Multi-Tenant arhitecture) in the same DB and it's working great. I can use EF bounded contexts and split domains appropriately. According to MSDN, ...
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50 views

Problems with queries [closed]

I have problems with queries in MySQL. Problem 1: Query: SELECT * FROM information_schema.TABLES WHERE TABLE_SCHEMA="mysql" and TABLE_NAME="servers" MySQL says: #1054 - Unknown column 'mysql' ...
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50 views

Maximum number of TEXT/BLOB columns per table/performance of table with many of them?

I've created a system that generically imports CSVs into a database table with metadata columns for keeping track of when a CSV record has been changed, and it allows filtering on CSV columns instead ...
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51 views

Migrate SQL server data to new schema

I have a database that was originally created by a couple of people for a small business unit (about 8 staff and 10 customers) in MS Access. The original 'developer' was a non-geek who had been sent ...
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31 views

OLEDB provider for linked server reported change of schema version error

I am trying to run a report but its giving this message: An error has occurred during report processing. (rsProcessingAborted) Query execution failed for dataset 'ParamYear'. ...
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25 views

Good reason to convert LONGTEXT column to smaller width if field is smaller?

We have a database that uses a LONGTEXT type for a column that does not need that much space. The maximum row size currently has about 6500 characters and that's with a few million inserts so it's ...
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64 views

ORA-00942: table or view does not exist- Can it be solved by granting privileges to user?

I am creating a Java application that connects to an Oracle Database. In the application I connect to the DB as User A, which works as intended. I then try to access tables in Schema 1 and Schema ...
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51 views

What is the name of the default schema in Oracle?

When you create an object in Oracle, and do not specify a schema (object prefix), is there a name for that default schema? I see in Oracle SQL Developer, that a newly created object shows up in the ...
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34 views

MongoDB storage of multi-dimensional arrays

Using MongoDB 3.0.7 as the primary datastore. I connect to it using ReactiveMongo 0.11 on a JVM-based language. My question is: how well does Mongo store multi-dimensional arrays? For image analysis, ...
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128 views

How would you design a table for approval system between User and Sports Club

I am currently learning database modelling and struggling to model the following requirement. I have a user and sports_club table. User can only join a sports_club if three existing users of the club ...
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49 views

How do I host and separate multiple projects on one Oracle Database?

From Difference between database vs user vs schema I'm trying to understand the concepts of the schema, user and database. My current understanding is you cannot create a schema separately. You can ...
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112 views

Documenting SQL Server Database [duplicate]

I wrote the following (Quick and Dirty) script to document a database schema: Note - The relationships part came from another guys site (I just can't remember where). Does anyone know how to ...
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689 views

Export pump all schemas except Sytem related schemas

I have around 111 schemas in one database instance and have to export all the schemas except the system related schemas to a new instance. Is there any way as to exclude system related schemas while ...
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75 views

Copying MySQL schema, some tables not getting recognized!

From the 'data' folder of my colleague I copied the entire 'MyDatabase' folder and pasted that in my own 'data' folder.Now, some tables are getting recognized while others are not.**All the tables are ...
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68 views

Can SQL Server 2014 schema be defined using ODBC?

I am trying to use the ODBC driver for SQL Server 2014 to export data from an Autodesk Revit 2015 model to a database. However, I would like to export to a default database (e.g. db1), creating a new ...
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870 views

Installing OE (Order Entry) schema in Oracle Express

I'd like to know if it's possible to install OE (Order Entry) schema in Oracle Express. If so, how can I do that?
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31 views

Do i need “CHECK CONSTRAINT” when i am using “WITH CHECK ADD CONSTRAINT”

I am working on SQL Server 2008 R2, where I generated a schema-only database script using SQL Server Management Studio. The generated script is as follows: ALTER TABLE [dbo].[ConsoleServer] WITH ...
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89 views

Database design: handling time

I am developing a weekly timetable which ideally would allow teachers pick what subjects they teach. While most of this is fairly straightforward, from a conceptual point of view I am unsure how to ...
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110 views

Schema Design with “Seasonal” Data

I am developing a SaaS web application for School Management. What I need help is this: The whole application is purposed for the current year that the School is in. However, some data and ...
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114 views

How can I limit a user to only be able to run procs in a schema, which access another db?

In a SQL Server 2012 SP2 Standard Edition instance I have a user in database A that needs to be able to run stored procedures in schema foo within that database. They shouldn't be able to do anything ...
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63 views

Normilsation - 2NF and 3NF

I've been through several questions and youtube tutorials, i understand that 2NF is removing the partial dependencies and 3NF is the transitive ones, but i can't get my head around how the following ...
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1k views

Select rows from table where each row refers to a different schema

I have customer table in public schema. And I have a schema named after each customer. Each customer schema contains different tables like portals, plugin, ... When I want to select portals used by ...
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29 views

Can we determine FDs if we are given some tuples?

I am taking a databases course and i'm learning about functional dependencies. I have searched around and did not find any information on this. My questions is if we are given a table with some ...
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1k views

In Oracle, how to get a list with the names of schemas that a user has read permission?

In Oracle, i need list which schemas a particular database user (or the current database user) has read permission. Based on this information, also need to get all the tables and views are in each ...
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61 views

Design for periodic data cuts

I've been building an application that has a 6-monthly update schedule, i.e. a cut of the data for H1 & H2 of each year. The previous version of this application implemented this by making a copy ...
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840 views

Migrating everything to do with a schema from one Oracle DB server to another

We have an old DB server, running Oracle 11g on Solaris. We also have a new DB server, also running Oracle 11g, but on RHEL. We want to move a schema to the new db - but we need everything it refers ...
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74 views

Can I update only the needed changes in a database?

First of all, I apologize if you can't understand very well what I am saying and it can be edit for better understanding of my post. The next example is for better understanding of databases with ...
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1k 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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167 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 ...
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195 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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320 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', ...
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2k 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 ...
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233 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 ...
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83 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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63 views

Create menu from multiple meals relationship

I have the following relations: Meals(meal_id, name, cuisine, ingredient) Users(user_id, name, username, password, email) Chefs(chef_id, name, username, password, email) I want to create the ...
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537 views

How can I Automate MongoDB schema design from existing MySQL Database and Logs?

I am working on the project which will automatically generate sample MongoDB schema analyzing existing MySQL database and logs. I am looking for help regarding the below questions. Please, share your ...