The logical model and/or physical design of a database.

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How to design relationship for racing team trades?

I'm working on a fantasy racing team project. I'm having trouble laying out the schema when it comes to the team table and the trades. I think I have the race, driver, and result tables laid out okay: ...
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1answer
102 views

How to/Where to find MySQL templates for Toad Data Modeler

I have recently install Toad Data Modeler 5.3.4 and it only has Oracle data model templates. Where can I find and import the MySQL data templates so that I can create MySQL database models. I have ...
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29 views

Modeling reference of two different table in same columns

I would like have advice to do the best choice to design my database model. Option 1 : I have 3 tables : Table descriptor : id_descriptorid_flowtype_flow Table real_flow : ...
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2answers
81 views

Elements inside a container: How to perform atomic operations on them?

In my DB (Postgres 9.4) I have the following items: Tshirts, Jeans, Shoes and Boxes. Tshirts, Jeans, Shoes can be placed inside a box and they can have a color (the color may be null). Each element ...
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33 views

Good Book for professional database design [duplicate]

I am currently working on a project with some friends and we are hoping to make a business out of it. We are at the database design phase and as a learning source I am using "An Introduction to ...
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1answer
72 views

MySQL error 1241: Operand should contain 1 column, INTERSECT two subqueries

I'm running this query in MYSQL and I'm getting the error 1241: Operand should contain 1 column(s). I want to know the names and student id's of the students enrolled in Database Management Systems ...
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1answer
26 views

Assign value to a field after checking a condition

I have this query: ALTER TABLE MERCHANTS ADD COLUMN merchant_image bytea, ADD COLUMN merchant_logo bytea, ADD COLUMN merchant_address VARCHAR(100), ADD COLUMN merchant_phone VARCHAR(50), ...
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58 views

How to selecting data from two queries using union?

I have three tables. I am trying to taking the data with two times interval after then subtracting from first two second for every possible row and getting the ledger report. Solution is given by: ...
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86 views

Database design recommendation for a workflow-enabled ticketing application

I am working on a ticketing application; tickets are created and they need to be resolved. A ticket needs to go through many steps (in this case 4 steps). Not just a single user in my application can ...
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1answer
41 views

db table column design question

I have a database that will track "location" in a building. Location1 contains country data. Location2 contains building data. Location3 contains room data. Each location table has a FK to the ...
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2answers
74 views

Making database tables 1NF

I am creating a database for a DVD rental shop, I have various entities that are related to this question, such as Film, FilmStar. For each film, you record its unique number, title, the year in ...
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20 views

Turn off Key constrain enforcement or change database structure?

I'm updating a POS system, it allow to make credits, orders, cuotes, and obviously direct sales, each of them have their own special properties, for example if the transaction its an order it must ...
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93 views

Foreign key to a subset of rows?

I have a table of Courses and it has a foreign key to Class_ID. A class teaches several courses dividing into several terms. So, Terminal is another table, it has a foreign key Class_ID to class ...
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10 views

Using db40 .db file in another pc

I am new to db4o. We are working on a team project in java using db4o and have inserted some objects in the database (say Cricketdb) on one pc. When I try copying the .db file and use it on my pc, it ...
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13 views

Organizing Educational Material

I worked with MC Access almost 10 years ago and not once since. Right now, I teach English and don't know any database lingo. I need some help in plain English. I've read some Q&A's here and it is ...
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50 views

Time complexity of query optimizer

I'm reading this article "How does a relational database work"(http://coding-geek.com/how-databases-work/) I'm confused by the section: Dynamic programming, greedy algorithm and heuristic. Using ...
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47 views

Can we combine Bitmap index with B+ tree index?

If I have a database of employees and expected queries on (salary,gender). Would it be a good idea to have a B+ tree index on salary and Bitmap index on gender at every leaf node of a tree. What are ...
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1answer
63 views

How does lock works when delete rows through secondary index in InnoDB?

step1: InnoDB Transaction Isolation Level Repeated Read. step2: Table schema CREATE TABLE `follows` ( `id` int(11) NOT NULL AUTO_INCREMENT, `followable_type` varchar(255) DEFAULT NULL, ...
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1answer
24 views

Normalising a database for monitoring stations

I have data about monitoring stations. For now it is stored in Excel tabs. I have decided to try to make a database. It will be my first contact with databases. Here is an example how it looks now in ...
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34 views

Are multiple paths between tables bad?

I have a system that builds online tests for school students. I have the following tables: SUBJECT (e.g. mathematic, science) INNER_SUBJECT (e.g. functions, matrix, multiplication) ...
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26 views

Fact Table with day grain that has many records that don't change

So I have a daily snapshot fact table that stores financial account balances. Normally, this would be pretty easy, just have a record for every day for every account. My problem is that table would ...
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1answer
62 views

Tables for two type of users in database. How to solve this problem?

This is the Entity Relationship Diagram I have created for my web application (based on Oracle APEX project). Two type of users can sign up and login and each user has his/her own profile and ...
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41 views

MySQL Multi-source - Single Slave Setup. Adding Unique Master ID on Master's tables definition

this is a design question. I understand that Replication, is like mirroring. So this would mean, whats on the master, should be mirrored on the slave. (Is this always the case, like strictly same ...
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52 views

Merge two data tables with different time preferably in access

I appreciate if I could help on this issue. I am relatively beginner to database designs. I have two tables (see link below) which I would like to combine: Tbl_1: Date, Product, Sold Tbl_2: Date, ...
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30 views

To Get Possible Conditions for provided Symptom and set of symptoms

Please look into my Schenario for symptom checker I am providing you sample table structure with sample data CREATE TABLE Symptoms ( ID INT, Title VARCHAR(100) ); INSERT INTO Symptoms VALUES ...
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1answer
187 views

How to manage very large amount of data in mysql

I have a table in MySQL in which I write logs of users in a specified format. It have just 2 columns:id (auto-increment), log. Currently data is very less, so I'm using this. Now there is a ...
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67 views

Design database table for property listing

I want to design a database for a listing website, this is the first time I design the database, so I am not sure if I in the correct path. Here is the fields that needed in a listing, title - ...
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28 views

Database normalization - Must all depedancies be preserved?

When converting to a higher normal form, must all functional dependancies always be preserved? for example: R(W,X,Y,Z) WX --> Y XY --> Z ZY --> W R1(B,C,D) XY → Z R2(C,D,A) YZ → W The ...
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1answer
53 views

Database design advice on a marksheet schema

I am not sure whether this type of question is allowed here, but seeing other questions, i think it is. I am doing a database design of processing exam marks. There is a marksheet for each of the ...
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1answer
81 views

Store parameters of various types

I am a (poor, young) scientist working to develop a database to allow a project to scale up. I am experimenting with MySQL and have had very encouraging experiences so far, but I am still novice and ...
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1answer
50 views

I have a database design for an E-commerce website. Need to know how to display related product for each specific product

For example: A customer is viewing a product on the website, say a laptop. There's a section on the left where i need to display products from the database that are associated with this particular ...
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1answer
181 views

How to setup sync between MongoDB and C# .NET Application

What is the best practice to synchronize a MongoDB remote database with a C# .NET App that would allow queries to be responded to within the local file system and update itself when there is a change ...
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1answer
96 views

Linking MS Access 2010 to Outlook Inbox: Including Attachments

I'm trying to set up a MS Access table linked to an Outlook folder. I've been able to use the external data wizard to set up a linked table, but the table seems to only include subject lines and ...
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111 views

User is An employee. Role or relation

I've created a database based on a party-model. In short I show you the tables: parties, kind, party_to_party_relations, role, party_roles table parties: CREATE TABLE `parties` ( `id` int(11) NOT ...
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1answer
50 views

Is it good to save Keywords stored by users in a new DB schema?

My question is more from the schema design and of further performance of the DB. I'm designing a DB schema which will store primarily strings. Actually, users work on these string, as normal mortals, ...
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3answers
64 views

How to design a Table in which its fields varies on its categories?

I am trying to design a database to post free ads. Eg http://www.gumtree.com.au/p-post-ad.html Scenario: Every ad will have different categories and some categories will have further sub categories. ...
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1answer
31 views

Slow query - just error count

I deal with slow queries in whole project. I indexed heavily but the results are nowhere. I had a lot of logs (thousands per minute) from SCADA systems and I am trying to count them for each SCADA ...
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51 views

mysql - suggestions for table design with huge number of columns [duplicate]

We have a table that consists of a huge number of columns (usually between 500 to 1000, depends on our clients websites). We are suffering from speed issues due to this, and we're looking for the best ...
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120 views

FastReport / Report Query Help - How do i convert a integer value into a string?

I am using FastReport to create my reports and I have an issue. I am trying to make a form with the data in ProductMaster.ITEMBUYINGPRICE. The output of this column is a 6-digit value showing the ...
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1answer
26 views

Are cut and paste of records from a table to another a correct pratice?

I am working on an app that does task dispatching. A user inputs a task with a start date and end date. The app gives the user a list of workers available and chooses to offer the task to some of ...
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50 views

Does MySQL InnoDB compression combined with Windows compression save more space?

We have a very large MySQL InnoDB database, compressed using the following syntax at the end of the table declaration: ENGINE=InnoDB ROW_FORMAT=COMPRESSED KEY_BLOCK_SIZE=4 We also have windows ...
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1answer
110 views

MySQL Circular Replication

I have this scenario where I have 4 MySQL servers (A,B,C,D), as this: Server (A) is always online, and serves as the main website. Servers (B,C and D) are online on random periods of the day, and ...
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2answers
48 views

MySQL - replicate some tables between transaction and report database

I have two different database (on two different hosts). One database is transactional and another database is reporting. Let us say, it stores information about departments and their employees. ...
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11 views

Where to put a 0..1 fk column when already having 0..n fk’s on one side and 0..1 on the other

I have a transaction table that represents user’s credit transactions and two tables containing different entities, but both interacting with the transaction table. Say, payment_with_state and ...
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2answers
43 views

Multiple types of parts with multiple types of information (unspecified amount) [duplicate]

I'm having trouble designing a database for a project I was working on recently. It's to do with a garage management system. So I've realised I need to store multiple types of parts (Tyres, engines, ...
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31 views

database polymorphic associations: design for foreign key point to itself

I have a database design that used to solve polymorphic assocations problem. Here is my schema: Post(PostID, PostType) Question(QuestionID, QuestionTitle, QuestionContent) // QuestionID references ...
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1answer
52 views

Should we store sum of values in a column, or store in memory database

I have a bunch of questions and answers and total votes of those questions and answers. My requirement that I always show how many votes for a question or a answer (and user doesn't often click to who ...
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1answer
49 views

Using Year Ranges vs Row for Each Year

I'm working on a database in SQL Server for a project. My background is in data analysis and although I'm familiar with database design I don't have a lot of experience. The project revolves around ...
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31 views

Help for design DB, avoiding circular relationships

Help for design DB, I have user, order, scratch_card and transaction tables. When user place an order, one record will add to order and another one to transaction as withdraw and when user recharge ...
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38 views

SSAS bridge table with Slowly changing dimensions

I am designing a datamart using the basic principles of Kimball for use in SSAS. I have a many many to many attribute relationships (multi-valued dimension objects), however I have a few questions: ...