Questions tagged [sql]

Structured Query Language (SQL) is a language for managing data in relational database management systems. This tag is for general SQL programming questions; it is not for Microsoft SQL Server (for this, use the sql-server tag), nor does it refer to specific dialects of SQL on its own.

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204
votes
14answers
99k views

“Never do in code what you can get the SQL server to do well for you” - Is this a recipe for a bad design?

It's an idea I've heard repeated in a handful of places. Some more or less acknowledging that once trying to solve a problem purely in SQL exceeds a certain level of complexity you should indeed be ...
193
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13answers
143k views

Why use a database instead of just saving your data to disk?

Instead of a database I just serialize my data to JSON, saving and loading it to disk when necessary. All the data management is made on the program itself, which is faster AND easier than using SQL ...
44
votes
9answers
11k views

Why is filesystem preferred for logs instead of RDBMS?

Question should be clear from its title. For example Apache saves its access and error logs in files instead of RDBMS no matter on how large or small scale it is being utilized. For RDMS we just have ...
32
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2answers
13k views

What's the history of the non-official pronunciation of SQL?

SQL is officially pronounced as /ˌɛskjuːˈɛl/ like "S-Q-L", as stated in Beaulieu, Alan (April 2009). Mary E. Treseler. ed. Learning SQL (2nd ed.). Sebastapol, CA, USA: O'Reilly. ISBN 978-0-596-...
191
votes
17answers
56k views

Is it good practice to always have an autoincrement integer primary key?

In my databases, I tend to get into the habit of having an auto-incrementing integer primary key with the name id for every table I make so that I have a unique lookup for any particular row. Is this ...
21
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4answers
17k views

Maintaining referential integrity between a mobile client and a server

So I have a relatively simple system. A mobile client creates records in a sqlite database that I would like to have synced to a remote SQL server (that is shared with other mobile clients). So when I ...
13
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3answers
902 views

Is reliance on parametrized queries the only way to protect against SQL injection?

All I have seen on SQL injection attacks seems to suggest that parametrized queries, particularly ones in stored procedures, are the only way to protect against such attacks. While I was working (back ...
10
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3answers
4k views

XML vs SQL for small projects?

I'm working on a small project which will only have one user at a time since it's a local application (developed in WPF and C#). To store data I was thinking of using an XML file but I'm wondering if ...
6
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2answers
12k views

Database model for keeping track of likes/shares/comments on blog posts over time

My goal is to keep track of the popular posts on different blog sites based on social network activity at any given time. The goal is not to simply get the most popular now, but instead find posts ...
96
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10answers
51k views

Why is “Select * from table” considered bad practice

Yesterday I was discussing with a "hobby" programmer (I myself am a professional programmer). We came across some of his work, and he said he always queries all columns in his database (even on/in ...
22
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2answers
10k views

SQLite with two python processes accessing it: one reading, one writing

I'm developing a small system with two components: one polls data from an internet resource and translates it into sql data to persist it locally; the second one reads that sql data from the local ...
35
votes
3answers
35k views

self referencing tables, good or bad? [closed]

Representing geographical locations within an application, the design of the underlying data model suggests two clear options (or maybe more?). One table with a self referencing parent_id column uk - ...
14
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2answers
9k views

Why NoSQL over SQL? [duplicate]

Possible Duplicate: When would someone use MongoDB (or similar) over traditional RDMS? How well the SQL and NoSQL go head-to-head. I read somewhere that SQL databases are not well for data that ...
28
votes
6answers
5k views

What good reasons are there to capitalise SQL keywords?

There seem to be a lot of developers who write their SQL by capitalising the keywords: SELECT column FROM table INNER JOIN table ON condition WHERE condition GROUP BY clause HAVING ...
17
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6answers
9k views

Code formatting SQL queries

Should I break SQL queries in different lines? For example in the project I am working on, we have a query that is taking 1600 columns! 1600 + tab chars. I wrote queries like this: "SELECT bla , ...
15
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4answers
2k views

Why do relational databases only accept SQL queries?

As far as I know, most relational databases do not offer any driver-level API for queries, except a query function which takes an SQL string as an argument. I'm thinking how easier it would be if one ...
0
votes
1answer
1k views

Search for object in loop or query? Who has better performance?

I have a DB that stores some complex objects of my app. When my app starts I load the objects into list and store them on the RAM. But sometimes I would like to search for an objects that fulfills ...
2
votes
3answers
473 views

At which point using string-based enums can become a real problem?

This is a direct follower to this question. An answer given to that questions says (my understanding), that nowadays using string-based enums instead of integers isn't a much problem, because hosting ...
1
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5answers
2k views

Designing pricing table (RDBMS agnostic)

I'm designing a price list table for my database. It will include Customer, Model, Start_date, End_date, Price, Currency, RRP When I update a new price list, which is sent every now and then (maybe ...
97
votes
4answers
69k views

why are noSQL databases more scalable than SQL?

Recently I read a lot about noSQL DBMSs. I understand CAP theorem, ACID rules, BASE rules and the basic theory. But didn't find any resources on why is noSQL scalable more easily than RDBMS (e.g. in ...
209
votes
19answers
122k views

Why is naming a table's Primary Key column “Id” considered bad practice? [closed]

My t-sql teacher told us that naming our PK column "Id" is considered bad practice without any further explanations. Why is naming a table PK column "Id" is considered bad practice?
28
votes
6answers
62k views

Using a relational database vs JSON objects for event/activity data

I am working on a project where I am trying to decide between using a standard SQL relational database or JSON objects to store data about an event or activity. The project will store data on ...
16
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4answers
4k views

Databases: Where should the application logic run? [duplicate]

http://highscalability.com/blog/2010/11/9/facebook-uses-non-stored-procedures-to-update-social-graphs.html talks about how Facebook moved logic out of the database into the application in order to ...
43
votes
7answers
93k views

SQL Triggers and when or when not to use them.

When I was originally learning about SQL I was always told, only use triggers if you really need to and opt to use stored procedures instead if possible. Now unfortunately at the time (a good few ...
18
votes
8answers
16k views

How would you design a user database with custom fields

This question is around how should I design a database, it can be relational / nosql databases, depending on what will be the better solution Given a requirement where you'll need to create a system ...
28
votes
2answers
14k views

Why store flags/enums in a database as strings instead of integers?

I've been browsing SQL dumps of some famous CMSes, including Drupal 7, Wordpress (some quite very old version), and some custom application based on Python. All of these dumps contained data with ...
14
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5answers
11k views

What are questions to test a programmers knowledge of SQL? [closed]

What are questions to test a programmers knowledge of SQL? What is the answer to the question? And what would a lack of an correct answer mean in terms of time likely to understand the concept(s) ...
26
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2answers
19k views

Why does convention say DB table names should be singular but RESTful resources plural?

It's a pretty established convention that database table names, in SQL at least, should be singular. SELECT * FROM user; See this question and discussion. It's also a pretty established convention ...
23
votes
4answers
5k views

Why many designs ignore normalization in RDBMS?

I got to see many designs that normalization wasn't the first consideration in decision making phase. In many cases those designs included more than 30 columns, and the main approach was "to put ...
61
votes
6answers
4k views

Is this a ridiculous way to structure a DB schema, or am I completely missing something?

I have done a fair bit of work with relational databases, and think I understand the basic concepts of good schema design pretty well. I recently was tasked with taking over a project where the DB was ...
41
votes
6answers
10k views

Why not return dates as a string from the database?

In a typical web application, dates are retrieved from the database layer strongly typed (e.g. in c# as a System.DateTime as opposed System.String). When a date needs to be expressed as a string (e....
5
votes
2answers
4k views

Why is NoSQL better for this scenario?

Hypothetical scenario: Let's say we are downloading JSON from Facebook with details of a user's friend's checkins, posts, etc... These come in as one document per friend per activity, so with 8 ...
28
votes
6answers
4k views

Why SQL is not so widespread in large desktop applications?

As a software developer, I've worked on projects ranging from tiny home-made apps to medium-size enterprise applications. In nearly every project I used a database or regretted choosing not to use it ...
5
votes
4answers
5k views

What is the “correct” way to store functions in a database?

Note: Yes, I know that storing functions in databases should be punishable by law. We are developing a financial web application using PostgreSQL, Sinatra and AngularJS. As you may have guessed, a ...
7
votes
6answers
2k views

Is the “One Description Table to rule them all” approch good?

Long ago, I worked (as a client) with a software which use a centralized table for it's codified element. Here, as far as I remember, how the table look like : Table_Name (PK) Field_Name (PK) Code (...
7
votes
1answer
14k views

Entity Framework vs. Linq to SQL? [closed]

I'm a little bit confused about these two terms "Linq to SQL" and "Entity Framework". I have the general idea that both of them somehow allow you to refer to database tables as .net objects or ...
4
votes
4answers
1k views

What are the arguments for/against Code Generation?

I'm in a position where we've got some brittle code that constructs SQL-like queries via text concatenation with parameters for inputs. The data source that it queries is fast and scalable but lacking ...
3
votes
1answer
5k views

What is the best way to store a formula in a database for a table driven formula? [closed]

So I am changing my code over to a table driven formula system to make it sustainable in the long term. So basically I have 5 foreign keys that will get me to a single formula to use. However I'm ...
3
votes
1answer
407 views

Creating a online database creator

I've been thinking of creating an online database creator (think DabbleDB, Zoho Creator, Intuit Quickbase, etc.). I've been thinking of a couple solutions: Have 4 database tables: Tables, Rows, ...
10
votes
6answers
2k views

What kind of Web development projects benefit from using ORM?

I'll start by saying that I've done 95% of my database work using SQL. Recently, I did some investigation of various ORMs, such as NHibernate and Doctrine. I can see the advantages of not needing to ...
7
votes
1answer
3k views

Raw Sql vs SqlAlchemy when Django ORM is not enough

In a django project, if a situation comes that Django ORM is not able to execute some complex queries then there are 2 options: Use Raw Sql queries Use SqlAlchemy I want to know if there are some ...
3
votes
4answers
4k views

Should I be learning Linq, Direct SQL Commands (in .net), EF or other? [closed]

Basically, I have a very good knowledge of plain old SQL coming from Classic ASP programming. Over the past couple of months, I have been learning C# and today was my first full day at MVC 3 (Razor) ...
2
votes
5answers
2k views

How to handle or prevent all Admins and users being removed

I have a website that stores all users in a database. A user can log on to the website and if they have sufficient privileges can add/delete users, as well as change their privileges. How do I ensure ...
14
votes
6answers
3k views

Do You Still Need Indexing After Database Normalization

After you have done a good normalization, do you still need to index the table? How is this going to affect the performance? Will it even affect the performance in some way after a good normalization? ...
5
votes
6answers
5k views

Confusion about proper use of * wildcard in SQL [duplicate]

Suppose I was writing an address book application where the details of each contact were stored in an SQL database. A user wants to know all the details for a person whose name is "Bob [Someone]". ...
4
votes
2answers
2k views

Deep SQL relationships to a C# object model

I have a database with deep table to table relationships for example Clients (one to many) -> ClientData (one to many) -> ClientJob (one to many) -> ClientProcess (one to many) -> ...
3
votes
2answers
884 views

Where should SQL/DB Queries be encapsulated in a software system?

I frequently write small applications (either web based or otherwise) that require heavy database usage. i've attempted various ways of handling where to put the actual sql queries (sort of ad-hoc ORM ...
2
votes
3answers
4k views

How to design ER diagram to allow for retrieving of product option pricing data?

I'm looking for a way to organize database tables when it comes to handling product option pricing retrieval and also storing pricing history for my use case. What I have I have a custom-made ...
0
votes
2answers
12k views

Best place to write SQL queries

I've been working on this project for my company. Currently I am embedding my SQL statements inside the program itself as and when they are needed. I do have two seperate classes - QueryBuilder ...
10
votes
2answers
764 views

Are (basic) SQL queries semantically equivalent to Higher Order Functions?

Is SQL basically a domain specific instance of map + fold + filter? It seems to me that the following SQL: SELECT name FROM fruits WHERE calories < 100 is just syntactic sugar for the following ...