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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2answers
108 views

Does sql use hastables for indexes? [closed]

Are there other ways of indexing?, Which are the more used? Does sql have an standard for indexes, it uses hash tables?
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4answers
478 views

Data Model - How to better model this circular reference

I'm designing the data model for a project where users can create documents, save revisions of that document that can be reverted to, and publish documents. The basic data model I have right now is ...
3
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1answer
5k views

Getting data from a database with the MVC model

I am creating an application which will have a very large database to draw it's information from (a student registration system to be exact). The database is created with Microsoft SQL Server if that ...
5
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3answers
7k views

How to test data based on SQL queries?

I'm trying to set up a test framework for (SQL) datasets that get updated daily. I want to write assertions that involve comparisons between two tables–for example, the sum of column visitors in the ...
3
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1answer
900 views

How is one or more aggregate function implemented in most SQL engines?

In the book Database Fundamentals, Silberschatz. It is explained that aggregate functions can be calculated on the march. This make sense. What it means is that for calculating the maximun, average ...
4
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3answers
3k views

What to do with database foreign keys in an entity class?

I know that an attribute defines the state of an object. So, is it correct to keep attributes that don't define the state of an object of a class? For example, I have an Employee class, which has ...
7
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4answers
1k views

Encapsulation for complex queries

I tried asking this question first on StakOverflow in a more concrete manner, but after being pointed here I realized I should rephrase it in more general terms; however, you can still review the ...
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2answers
1k views

Registration form with email verification

Can someone point me in the right direction: I need to make a website with a registration form, to create accounts with e-mail verification, to write the forms content in a database table or something ...
2
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0answers
430 views

ODBC 3 Multiple Statements vs Multiple Connections

So right now I have a single thread to handle all the requests for the database. Let's say I have 400 requests per second for logins / logouts / other stuff, and 400 requests per second which are only ...
0
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1answer
89 views

Why storing a payroll in XML type field would be good or bad

We have a PAYROLL issues by the client to make it dynamic i.e. to make the whole process computerized. It includes: Employees Allowances (Scale wise, which could change yearly or monthly or ...
0
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3answers
128 views

Getting RowCount without wasting resources

I have a large SQL query that relates 6-7 different tables and returns fourteen different rows as distinct sets, in a union with an equally-large query, that at times can return over a thousand ...
6
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4answers
3k views

SQL Query and Java Constant Abuse?

I am currently charged with taking over a lot of code that is written with fields names placed into Java constant at the top of the file, and then the SQL queries constructed using string ...
1
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1answer
463 views

auto generated web CMS for pre-existing SQL db?

What I'm looking for is a way to auto-generate a simple web-based CMS for a simple pre-existing SQL database. To be used by 'app administrators', not the general public. Something that: allows basic ...
3
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1answer
505 views

More scalable alternative to a transaction-per.request in a SQL+REST stack?

I'm new in web programming with SQL database. So please forgive my ignorance. I'm using some modern framework to make a REST server with a SQL database. I'm using transaction only when I think I need ...
2
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2answers
1k views

SQL query or C# .net code for csv files import?

My aim here is to find out the best possible and feasible solution for my dilemma. I want to import some csv file (may contain around 50~60K records) into database after some manipulation into the ...
4
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2answers
113 views

Why are triggers seen as a last resort to solve multiple paths in cascading deletes?

There is a problem using ON DELETE CASCADE on foreign keys in a SQL database if there are multiple paths from the root foreign key to the leaf. The way around this seems to be to replace the ON DELETE ...
2
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2answers
541 views

Why use JSON dataset rather than SQL Query?

A colleague was asking me to explain a system information flow, as they are having problems with the wrong information being presented. It seems that what they have created is a custom built website, ...
0
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1answer
738 views

Relationship between REST APIs and Databases [duplicate]

I've been studying databases and rest APIs lately and I have a question about the relationship between the two. Imagine I have a database with three tables, STUDENTS, ENROLLED, and CLASSES. STUDENTS ...
3
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1answer
714 views

Best practices for dashboard of near real-time analytics

I’m currently building a dashboard to view some analytics about the data generated by my company's product. We use MySQL as our database. The SQL queries to generate the analytics from the raw live ...
3
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4answers
805 views

Keeping a ratio column that's the division between two other columns

I'm about to build a SQL table where I want to store currency orders. That means that I need to store how much I paid for a certain quantity, and the ratio between both quantities. So for example: +--...
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1answer
63 views

Querying Results from End of the table

Normal behavior of the SQL Table is to add new rows in end of the table. I want to query results of single row only. So mysql command is SELECT id FROM users WHERE country='india' LIMIT 1 this ...
8
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1answer
2k views

Using MySql 5.7 JSON columns for EAV

I am developing an e-commerce product and I have been able to implement all functionality and am left with allowing users to create additional attributes for a product. Right Now I have two options. ...
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 ...
51
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8answers
16k views

Is the use of NoSQL Databases impractical for large datasets where you need to search by content?

I've been learning about NoSQL Databases for a week now. I really understand the advantages of NoSQL Databases and the many use cases they are great for. But often people write their articles as if ...
4
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2answers
302 views

How to represent a collection with capacity in a database?

Concerning normalization of a one to many relationship, I am not sure how to represent a collection with a specified capacity in a database. I can think of two ways to represent an entity A with a ...
3
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3answers
805 views

Relational table design for data ownership

Setup (schema simplified for clarity) Suppose I have a table called resource: +---------------+--------------+------+-----+ | Field | Type | Null | Key | +---------------+-----------...
1
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1answer
86 views

How to handle multiple “valid after {date}” in a performant way

We work on an Application which displays a duty roster and also some other DateTime related things. So my Database is full of Relations like in this small Example: This results in big ...
3
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1answer
263 views

Django Migrations: Binds data to code?

If you have custom code for models (custom validators and custom fields are examples), Django Migrations will import them directly into the migration files. An example: file web/models.py def ...
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1answer
146 views

MS SQL Server Cell level Encryption options [closed]

Recently, i got the task of doing some research into the data encryption at the cell level. I tried using the Symmetric key (by passphrase) & second option i took is Symmetric key (by Certificate)....
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2answers
84 views

Working with local connections instead of global

In recent weeks I became very concerned that the way I've been working with database connections for the past years, is simply wrong. I exclusively create a new connection for each database operation ...
1
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4answers
564 views

How to deal with long running transactions?

I'm developing a Content Management System (CMS) and I would like to include a "Save Changes" button. I mean: a user performs several changes in the database, but those changes are still not available....
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1answer
56 views

Database multiple database query each time

I'm writing a rest service. For each request I use about 4-8 queries. Should I try to refactor those into a single query?
1
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3answers
845 views

Long running DB query with concurrent write at the same time [closed]

We have a big table with a lot of data and a select query which takes 3 seconds to run. However we are a highly concurrent environment and each second we get 100 new records in our database. So let'...
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) -> ...
0
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1answer
103 views

SQL Table With A Call To Action?

This is all done in Microsoft Access 2007 and SQL Server. We are creating a way for our users to quickly make notes on a customer. These quick-notes will contain tags that will prompt the user for ...
4
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2answers
261 views

Database constraints for a recursive folders structure

In an application, I have a recursive folder structure (like folders in OS X or Windows file system). Each folder can contain three kind of things: Other folders (hence the recursive structure) ...
2
votes
3answers
749 views

automatic database fill up in sql script tests

The problem I am working on an application with ~ 1000 tables in a sql server database. I am having a recurring issue with a sql script. The script is used by the consulting team to "clean" some ...
3
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1answer
214 views

How do SQL transactions return immediate results?

I am using transactions to do bulk insert/updates. This is my little test loop: $now = date('Y-m-d H:i:s'); for ($i=0; $i<60; $i++) { $db->insert($cfg['ps_manufacturer'], array( '...
0
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3answers
371 views

Why does databases use text? [closed]

This might be a little dumb question but why do we save text in the db instead of something smaller? Couldn't there be some other way to store data in the db like in a compressed form, and then have "...
0
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1answer
231 views

What is the problem will happen if I create auto generate ID without using mysql auto increase of mysql table by my self?

I would like to ask you a question about MySQL AUTO_INCREMENT. I already created my own function to generate AUTO_INCREMENT when the user inserts any data input a table in MySQL. This function works ...
6
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1answer
2k views

Clean Architecture - How to go from “Database Driven” to “Independent of Database” [closed]

I am looking for some clarity and hopefully some advice on writing clean architecture for a large system. My Companies "Web Solution" is +-10 years old, my job is to rewrite it. It is written across a ...
1
vote
1answer
644 views

Why do I need to use recursion on the classic employee manager database relationship?

Take the data from the Oracle scott database. I have modified it to have multiple levels of management from the original, select * from scott.emp order by mgr desc; empno ename job ...
-1
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1answer
181 views

behaviour of SQL BETWEEN operator [closed]

This is kind of philosophical question... Today i spent way too much time to debug a method which was generating a SQL command. I figured out the error was because the code was generating something ...
22
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4answers
3k views

Why not just make non-parameterized queries return an error?

SQL injection is a very serious security issue, in large part because it's so easy to get it wrong: the obvious, intuitive way to build a query incorporating user input leaves you vulnerable, and the ...
2
votes
3answers
764 views

Time attendance module design

I am working on time attendance module and I managed to read the data from the timing machine in the following format: Id CheckIn Type Status 0000142 5/15/2015 6:00 PM 2 OK ...
0
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1answer
315 views

Optimizing instant notifications

Scenario To deliver instant notifications to the client, I'm sending an AJAX request to a PHP page that checks if there are new notifications: if there are, it outputs them, otherwise it sleeps for ...
1
vote
1answer
269 views

Web framework in pure SQL

I heard that SQL is Turing complete language (for example: https://stackoverflow.com/a/7580013/2604170) I am just curious if would be possible to create independent web framework like Ruby on rails or ...
25
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2answers
18k 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 ...
3
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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 ...
1
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2answers
914 views

Partial Update of Database Table

I have a database table with numerous fields including "category". The source of this table is an xml file which the system receiving occasionally. Each xml file contains data for one category. The ...