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Questions tagged [relational]

526 questions
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Is this natural join operation used correctly? (Relational Algebra)

I have the following task given from the professor:R-E Modell Assume the companies may be located in several cities. Find all companies located in every city in which “Small Bank Corporation” is located. Now the professor's solution is the…
hikari_temp
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What's the difference between an In-memory database and relational database + NoSQL Database?

it seems that databases can be divided into relational dBs also called SQL databases and NoSQL databases. My question is where do in-memory-databases fit into this picture? I only find in-memory-databases use the main memory as data storage instead…
Red King
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Tricky relational DB design question

I have a tricky problem that I've been messing about with for a few days now and cant find an optimal solution for. These are my tables: site site_node page The site node table contains a list of nodes representing a hierarchy (using nested set).…
Jack Sleight
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Group key-value columns into a rows per group with column per key

I need to show groups of key/value pairs with n keys stored in a MS SQL Database in a table with one record per group and one column per key. I found that example but in my case the keys (finally the columns) are not fix and must come from the…
Dirk Leuther
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How do you filter the user with hasRole() in Laravel 5 within relational query?

I want to filter my query and return only if the user hasRole "Premium" and limit the result to 10. Along with this query is a count of records which Conversion has and sort it in DESC order by total column. Right now I have a working query that…
moreishi
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Is there !< and !> in JavaScript?

Someone told me that there's !< and !> in JavaScript. I tried it but it didn't work. Is there something like this in JavaScript? If not in JavaScript, is it there in any other language?
Mohammed Shoaib
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Is my Relational Algebra correct?

I have a database assignment which I have to create some relational algebra for two problems. I feel fairly all right with the majority of it, but I just get confused when trying to project attributes out of a table which is joined to another…
Malachi
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Lucene.NET: How to use BlockJoinQuery?

I am trying to do a relational search with Lucene.NET 4.8 (actually I compiled it using the latest sources) by following this post. I reference Lucene.Net, Lucene.Net.Analysis.Common, Lucene.Net.Grouping, Lucene.Net.Join, and…
Jack Miller
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relational algebra to SQL converter or vice versa

i would like to check if my relational algebra statements are correct, so is there a program out there that outputs relational algebra equivalent of an SQL query?
şaloma
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Symfony entities without relational

I work with Symfony2 and Doctrine and I have a question regarding entities. In a performance worries, I'm wondering if it is possible to use an entity without going all the associations? Currently, I have not found another way to create a model…
Vincent
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Appropriate algorithm for offline bidirectional data synchronization

Given: Relational database table information (postgres) that represents company information and user information. The company and user data is downloaded to the mobile app as two .sqlite files, which can be joined and viewed using sql (minimizes…
Joel
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Validate math expressions including relational operators

I am facing a situation, where a user is allowed to define some conditionals as follows: x >= 2 x < 6 y >= 2 y > 2*x where x and y are variables. Does a library exists in Java or Python that is able to compute the domain range for each variable…
labrassbandito
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Relationships in SQLalchemy

SQL Alchemy handles adjacency structures just fine, e.g. a self-referential table node where foreign key node.parent_id relates to primary key node.id. I have a less conventional model where a node has two parents (a genealogy database). In this,…
Blackmyre
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Relational Query Parse.com android

So I'm Implementing an app using Parse.com as back end, There is basically 3 class in Parse. The first one User where I have the User's Information, and Gallery where I have images "like Instagram, and Finally Follow Class where I have the relation…
Ran
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Basic database relations

I recently opened a travel agency and I need a database but don't have the money yet to have it done by a professional... A very basic thing will do until I can have it done better. We do "Transfer" services from airport to hotel and "Tours" with…
Alby
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