Questions tagged [database]

This tag is for general database questions; if you question is specific to SQL use that tag instead.

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12
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5answers
1k views

How to avoid violating the SRP in a class to manage caching?

Note: The code sample is written in c#, but that shouldn't matter. I've put c# as a tag because I can't find a more appropiate one. This is about the code structure. I'm reading Clean Code and trying ...
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2answers
20k views

How are abstract database interfaces written to support multiple database types?

How does one begin to design an abstract class in their larger application that can interface with several types of databases, such as MySQL, SQLLite, MSSQL, etc? What is this design pattern called ...
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5answers
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Indexing a database

I am not so familiar with databases and now I am trying to understand the indexing mechanism. From what I know, in a RDBMS, indexing on a column makes searching by that column faster. This is also ...
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4answers
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Best approach for a database of long strings

I need to store questions and answers in a database. The questions will be one to two sentences, but the answers will be long, at least a paragraph, likely more. The only way I know about to do this ...
12
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4answers
9k views

Is storing a list of strings in single database field a bad idea? Why?

Recently, I started to work on some legacy system. People that developed it, came to an idea to store list of strings in single field of database table. Lets say that it is an identifier for object ...
12
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5answers
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Agile methods and Databases at the start of the project

New to agile and I'm not sure how to start. The idea is to create small parts of the project in sprints. However the project I'm working of requires a database and the database must be almost ...
12
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3answers
2k views

Creating a layer of abstraction over the ORM layer

I believe that if you have your repositories use an ORM that it's already enough abstracted from the database. However, where I am working now, someone believe that we should have a layer that ...
12
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4answers
16k views

C# Minimal SQL Database

I'm working on a small project (not production) where I'm needing to store enough data that something like a CSV would be inefficient to process and an SQL/MySQL server would be too much. Does .Net ...
12
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2answers
350 views

Should I lock rows in my cloud DB while they're being edited by a user

I am creating a desktop application that persists the data in the cloud. One concern I have is a beginning to edit an item in the application and leaving it for a while causing the data to become ...
12
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8answers
2k views

Best way to model a singleton in a relational database

When designing relational database schema for web applications, I often find a case where I end up creating a table just to contain one row, and only one row. It feels like that is the wrong way to ...
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7answers
6k views

How do you handle database security from a desktop application?

For about 10 years I've worked on various in-house desktop client applications with SQL Server data stores. Rarely did I start these projects - most are takeover work. One thing that seemed constant ...
12
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4answers
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What would you think about a new Java persistence tool, that's not really an ORM? [closed]

Persistence in Java Over the past years, I have gathered experience in the field of persistence abstraction in Java, using concepts such as EJB 2.0, Hibernate, JPA and home-grown ones. They seemed to ...
12
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5answers
789 views

My team is scared of relational database entities with foreign key relationships and I don't understand why

I'm relatively fresh out of college so most of my familiarity with relational databases is from my databases course where anything not in BCNF or 3NF is a travesty. Certainly that's one end of the ...
12
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1answer
9k views

Log to file or to database table?

I'm developing a web application which uses MS SQL for various data: including users, user accounts, user licenses, license prices, invoices. I need to log users' real-time usage of the system, and ...
12
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3answers
12k views

Should backend IDs be public or not on a REST API?

Based on what this guy says: http://toddfredrich.com/ids-in-rest-api.html Let assume he is right about using UUID to identify the api resources. Then I run into troubles trying to implementing it ...
12
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2answers
49k views

How to get real time notifications, when a database change (insert, update, delete) occurs?

I'm creating a dashboard which should monitor a database table. I have only database access (no application layer). The table is rather large (10 million rows), however not changing rapidly (100 ...
12
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4answers
561 views

Can I use the database structure of an open source project?

I found a database structure for a CMS system and I want to copy it with the EF that this database is done in, is it OK to copy the database structure of open source software which is under GNU v2 ...
12
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2answers
311 views

How do you design your software that updates several microservices, if one of them fails?

Is there a design pattern or practice I can use to help with services that are either down or go down, while others are stable? What if I have three microservices, and two of them are good, and one ...
12
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4answers
31k views

When should we use weak entities when modelling a database?

This is basically a question about what are weak entities? When should we use them? How should they be modeled? What is the main difference between normal entities and weak entities? Does weak ...
12
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4answers
13k views

Business Objects within a Data Access Layer

So I've been creating a data access layer via TDD and have approached somewhat of a concern. I'd rather not start down the wrong path, so I figured I'd ask you guys to see if my thoughts were in line ...
12
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2answers
2k views

Persisting natural language processing parsed data

I've recently started experimenting with natural language processing (NLP) using Stanford's CoreNLP, and I'm wondering what are some of the standard ways to store NLP parsed data for something like a ...
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10answers
1k views

How could RDBMSes be considered a fad?

Completing my Computing A-level in 2003 and getting a degree in Computing in 2007, and learning my trade in a company with a lot of SQL usage, I was brought up on the idea of Relational Databases ...
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11answers
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Is continuous creation and deletion of tables a sign of an architectural flaw?

Recently I had a discussion with a developer who mentioned that during program development, they routinely create and delete tables and columns on a regular basis while working on new features and ...
11
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5answers
825 views

If passwords are stored hashed, how would a computer know that your password is similar to the last one if you try resetting your password?

If passwords are stored hashed, how would a computer know that your password is similar to the last one if you try resetting your password? Wouldn't the two passwords be totally different since one is ...
11
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4answers
907 views

Class Duplication Pattern?

I'm currently working as a solo developer on my current project. I inherited the project from another developer, who has since left the company. It's a model-view-controller style web application in C#...
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3answers
2k views

Best Practices: Database app programming patterns

I have written many database (MySQL) web apps so far but I always think my structure is kinda clumsy. I want to improve the programming/design pattern I use, hoping for some advice here. Particularly, ...
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8answers
3k views

Unifying programming and database query [closed]

Consider a common tutorial for object-oriented programming languages like C++ or Java: create a simple order processing system with objects representing accounts, orders, items etc (or something more ...
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5answers
2k views

How to prevent two users from registering at the same instant with same username?

We cannot serialize registrations as there are millions of users registering at the same time. Parallel registrations need to happen. Let's say the database doesn't contain username 'user1'. When two ...
11
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5answers
17k views

Database connection - should they be passed as parameter?

We have a system whereby the database connection is get once using a common method, and being pass throughout the relevant class to be used. There are doubts that passing the database connection as a ...
11
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3answers
11k views

Models per database table?

I am using codeigniter, and have found myself in a similar situation where I have repeated Model methods. I am creating a Model per Controller. But I would creating a Model per database table be ...
11
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4answers
5k views

Keeping an enum and a table in sync

I'm making a program that will post data to a database, and I've run into a pattern that I'm sure is familiar: A short table of most-likely (very strongly likely) fixed values that serve as an enum. ...
11
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3answers
4k views

Unit testing vs Integration Testing [duplicate]

What is the difference between unit testing and integration testing when it come to web development (where 90-95% of the code relies on a database)? One thing I here all the time is that unit testing ...
11
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4answers
14k views

What is the best practice for saving TimeZones in the database?

We want to start collecting timezones for each of our addresses in the database. What is the best practice to store the timezones? How would you go about acquiring timezones for the existing address ...
11
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3answers
5k views

How do you put a database online? [closed]

I have a very beginner question regarding web development. I've had some experience with JSP, Hibernate, and MAMP to create a simple system for tracking inventory and sales. But this was all done ...
11
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2answers
12k views

Database Schema for Pricing Products (packages, promotions, qty based, limited time offer…)

I'm working on a new point of sale for a company that products for different prices depending on the product mix. All products have a base price. To explain my problem, I will use the following info:...
10
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22answers
8k views

Software Developer Interview Question - Fair or Unfair [closed]

I just phone interviewed with a company for a graduate software developer position and was asked the following questions. I should add that the company concerned are not a database vendor. How does a ...
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9answers
21k views

Is there a large bank using Mysql or PostgreSQL? [closed]

I always thought the largest scale of banks use Oracle. However, there is no proof they really use Oracle instead of Mysql or PostgreSQL, nobody knows the secret. Any idea what they really use? Can ...
10
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4answers
5k views

What are the differences between algorithms using data structures and algorithms using databases?

The General Question What are the differences between algorithms using data structures and algorithms using databases? Some Context This is a question that has been bugging me for some time, and I ...
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4answers
4k views

If a microservice architecture needs a separate database per microservice then it's too costly & unmanageable. Why do we even need it?

I read about microservices and it seems illogical to me to create a separate DB per service just to achieve isolation. I can achieve the same using only web services and a single database. Why do we ...
10
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2answers
2k views

Who designs databases in web development? [closed]

In the context of web development, who designs databases? Despite a whole host of information associating back-end web dev with server-side processing, data modeling, and the like, the database design ...
10
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5answers
717 views

Do I really need triggers for relational database, for example, PostgreSQL?

I know that triggers can be used to validate stored data to keep database consistent. However, why not perform validation of data on the application side before storing them into the database? For ...
10
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3answers
9k views

How should I encapsulate database access?

What are some examples of good class structures used to manage database access? I am a fan of class encapsulation and would prefer the containers (e.g. car) not to perform database tasks. I would ...
10
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4answers
5k views

Weaknesses with different types of NoSQL databases

Here's my question: What are the weaknesses with different types of NoSQL databases? Specifically, what're the weaknesses of key-value stores, graph data stores and document stores? I've had an easy ...
10
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5answers
7k views

How to decide between storage formats and what are example use cases for some of them?

We have different ways to store program data (save files in games, employee databases, program configuration etc.): Plain text (think .ini and .conf) XML Databases (MySQL, SQLite...) .zip and similar ...
10
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5answers
15k views

What is needed to deploy an application that uses Microsofts new LocalDB?

I'd like to know what microsoft components need to be installed for this new LocalDB to run on a users machine. Now in CTP3: SQL Server Express LocalDB LocalDB is a new lightweight deployment ...
10
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4answers
2k views

Should database queries be abstracted out of the page itself?

When writing page generation in PHP, I often find myself writing a set of files littered with database queries. For example, I might have a query to fetch some data about a post directly from the ...
10
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2answers
3k views

What is the algorithm for expiring items in key-value storage?

I was thinking on how current key-value storages implement "expire date" for items. Currently I have 2 variants for that in my mind: they don't do anything (keep expired data), and only do check when ...
10
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2answers
5k views

B Tree compared to an R tree - Isn't it just a bunch of linked lists linked together?

I'm pretty familiar with a B Tree, mainly having to keep the databases well fed with electricity, air conditioning, and harddrive space. I associate with a double (doubl[ie,ey]?) linked list. Today, ...
10
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4answers
283 views

What are possible ways to avoid duplicates when you can't add an unique index

I'm stuck in a concurrency problem. Is a typical problem where the user sends 2 o 3 transactions to persists some data that SHOULD NOT BE duplicated in the DB, in case of a duplicate record you ...
10
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5answers
5k views

Writing Web “server less” applications [duplicate]

TL;DR What are the prospects of writing applications which are completely based on a REST database server (CouchDB) and web applications which directly access the DB instead of having a web server in ...