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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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22
votes
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 ...
22
votes
6answers
20k views

At what size of data does it become beneficial to move from SQL to NoSQL?

As a relational database programmer (most of the time), I read articles about how relational databases don't scale, and NoSQL solutions such as MongoDB do. As most of the databases I have developed ...
22
votes
2answers
9k views

Is SQL declarative?

I ask because so many of the questions I see in SQL amount to: "This is slow. How do I speed it up"? Or are tutorials stating "Do this this way and not that way as it's faster". It seems to me that a ...
22
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2answers
35k views

Best way to maintain data between local and remote sql databases [duplicate]

So I have, what would seem like a common question that I can't seem to find an answer to. I'm trying to find what is the "best practice" for how to architect a database that maintains data locally, ...
21
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9answers
10k views

Whether to put the business logic in Stored Procedure or Not?

There is always a debate over the topic - "Whether to put the business logic in Stored Procedure or Not?". If we decide not to use the ORM Tool and not to put the Business Logic in Stored Procedure ...
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 ...
18
votes
4answers
583 views

Database abstraction — is it being overdone?

After being exposed to numerous database abstraction layers, I'm starting to wonder what the point is of every library inventing their own different paradigm to access data. Picking up a new DAL feels ...
18
votes
6answers
8k views

Interacting With Data Using Multiple Databases/Servers

All of the projects that I've had to deal with so far have only required a single database on a single server. I'm interested in learning more about how projects that need to scale move to multiple ...
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 ...
18
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2answers
2k views

Does F# offer anything particularly useful for database-driven web development?

My organization finally upgraded to MS Visual Studio 2010 this year. One of the big new features that Visual Studio 2010 offers is the F# programming language. I understand that F# offers a ...
18
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5answers
4k views

Reason to prefer RIGHT JOIN over LEFT JOIN

If I understand correctly, every RIGHT JOIN: SELECT Persons.*, Orders.* FROM Orders RIGHT JOIN Persons ON Orders.PersonID = Persons.ID can be expressed as a LEFT JOIN: SELECT Persons.*, Orders.* ...
17
votes
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 , ...
17
votes
7answers
8k views

What are the advantages to using SQL query builders?

Are there any advantages to using a query builder, rather than using raw SQL? E.g. $q->select('*') ->from('posts') ->innerJoin('terms', 'post_id') ->where(...) vs: SELECT * FROM ...
17
votes
2answers
18k views

Best method to implement a filtered search

I would like to ask you, your opinion when it comes to implement a filtered search form. Let's imagine the following case: 1 Big table with lots of columns It might be important to say that this SQL ...
16
votes
7answers
70k views

What is faster? Using REST API or querying a database directly?

What is faster performance wise? Creating a REST API and having your web app use the REST API to do all interactions with your database OR querying your database directly (i.e. using whatever typical ...
16
votes
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 ...
16
votes
7answers
4k views

How do you version/track changes to SQL tables?

When working in a team of developers, where everyone is making changes to local tables, and development tables, how do you keep all the changes in sync? A central log file where everyone keeps their ...
15
votes
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 ...
15
votes
7answers
745 views

To Domain or not to Domain

The SQL92 and SQL99 standards define CREATE DOMAIN DDL constructs. Not all databases support this, or have a different name for it (SQL Server has User Defined Types, for example). These allow one to ...
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? ...
14
votes
10answers
6k views

Why don't RDBMSes return joined tables in a nested format?

For example, say I want to fetch a User and all of his phone numbers and email addresses. The phone numbers and emails are stored in separate tables, One user to many phones/emails. I can do this ...
14
votes
7answers
3k views

Why is SQL known as a relation-based / functional language?

We're learning that most languages are classified as either of the two, "relation based" or "high level". I've never used SQL before, but from reading its syntax it seems more like the imperative/high-...
14
votes
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) ...
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 ...
14
votes
4answers
4k views

TDD with SQL and data manipulation functions

While I'm a professional programmer, I've never been formally trained in software engineering. As I'm frequently visiting here and SO, I've noticed a trend for writing unit tests whenever possible and,...
13
votes
13answers
1k views

Do SQL Devs create SQL queries using SQL Query Designers?

I was just curious if SQL Devs write their code freehand or do they make use of the visual query designer to generate queries? In the majority of the cases, the query designer can create most of non-...
13
votes
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 ...
13
votes
4answers
20k views

Database History Table / Tracking Table

Currently I want to structure a tracking/history table like this: PrimaryKey - ID OtherTableId - fk fieldName - name of the field its tracking OldValue NewValue UserName CreateDateTime So basically ...
13
votes
4answers
643 views

About my database date datatype crusade: Valid? Worthwhile? Does anyone else feel it?

I spend a lot of time answering SQL questions over on SO. I frequently come across queries of this ilk: SELECT * FROM person WHERE birthdate BETWEEN '01/01/2017' AND '01/03/2017' SELECT * FROM ...
13
votes
3answers
5k views

Best way to organize SQL queries stored in your code ? (or should you?) [closed]

I am sure I am not the only one who gets frustrated when they see a page of code littered with SQL queries. The ActiveRecord and other ORM patterns help mitigate a good amount of SQL used in a project,...
12
votes
4answers
2k views

Historical precedent for why Prolog is less popular than SQL in Imperative Programming? [closed]

It seems that writing Declarative SQL is very popular in Imperative Programming. However, it also seems that writing Declarative Prolog could save a lot of complexity but this is not very common. ...
12
votes
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
votes
2answers
6k views

How do you unit test \ use TDD methods for ETL's and reporting projects?

ETL projects are projects created using an ETL (Extract - Transform - Load) tool such as SSIS, PowerCenter,etc These typically involve reading data from an external source, loading it to a staging ...
11
votes
17answers
3k views

Is there still a need for writing SQL?

With so many ORM tools for most modern languages, is there still a use case for writing and executing SQL in a program, in a language/environment that supports them? If so why? For clarity: I'm not ...
11
votes
7answers
1k views

How can I get programmers to stop writing code vulnerable to SQL injection?

Sometimes you get busy and delegate small tasks to junior programmers. But if you don't pay close enough attention you find yourself with this kind of code in production: class DivtoggleController ...
11
votes
2answers
7k views

In what order are rows fetched absent ORDER BY clause?

One programmer is testing and comparing the same application which uses the same database structure, and the same data, only in two separate databases, one with Oracle 8 and one with Oracle 9. The ...
11
votes
4answers
567 views

How to review sql changes more effectively? [duplicate]

From my experience, sql code changes almost always tend to be NOT incremental: someone creates a new stored procedure, or modifies an entire embedded sql query for optimization purposes, or creates a ...
11
votes
3answers
3k views

Storing n-gram data

I was hoping to brainstorm a little bit on the subject of storing n-gram data. In my project, I am trying to solve linguistic problems where I know all (n-1) data items and want to statistically guess ...
10
votes
12answers
3k views

How is “SELECT *” read in English? [closed]

The other day, a friend told me that in USA, they pronounce SQL like squel, not es-qu-el. I was surprised. I was wondering how "SELECT *" is read/pronounced while talking. select star? select ...
10
votes
7answers
1k views

Nested Entities and calculation on leaf entity property - SQL or NoSQL approach

I am working on a hobby project called Menu/Recipe Management. This is how my entities and their relations look like. A Nutrient has properties Code and Value An Ingredient has a collection of ...
10
votes
6answers
12k views

Proper syntax formatting for SQL? [duplicate]

Is there are a widely accepted standard for formatting SQL queries? I've never been given any guidance as to the "typical" or "standard" way of doing it. I've seen three styles in the wild, and ...
10
votes
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 ...
10
votes
2answers
767 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 ...
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 ...
10
votes
2answers
18k views

Where to put a common database connection for my classes

I have several classes (Repositories) which do the task of saving/retrieving some objects in/from database; all of them need to establish a connection to one database. I thought in order to avoid ...
10
votes
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
votes
1answer
2k views

How to document an algorithm properly with sample data?

I am wondering what should an algorithm documentation contain? Can't locate a proper guideline to follow. I have in mind to include summary of the algorithm description of the algorithm flowcharts ...
10
votes
2answers
4k views

Algorithm for formating SQL code

I need a tool (for in house usage) that will format SQL code (SQL Server/MySQL). There are various 3rd party tools and online web sites that do it but no exactly how I need it. So I want to write my ...
9
votes
4answers
44k views

Best practice to query data from MS SQL Server in C#?

What is the best way to query data from a MS SQL Server in C#? I know that it is not good practice to have an SQL query in the code. Is the best way to create a stored procedure and call it from C# ...
9
votes
6answers
598 views

Software solution from the 2000's, should I attempt to patch or remake the whole thing?

I was sent out to discuss a system that a certain company is currently using and what should be done with it. The company manufactures various carton displays. This system was developed to keep track ...