Questions tagged [entity-framework]

For questions relating to Microsoft's object-relational mapper.

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Entity Framework 6: How can I add new column to existing table and at the same time update view (add column) in same migration file [closed]

Example in the EF6 migration file Up method. I wish to add a new column B in existing table Country. Sql("ALTER TABLE [dbo].[Country] ADD [B] INT DEFAULT((0)) NOT NULL;") Then I will need to ...
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23 views

Database design for multilingual tags

I'm looking for a simple database design for tags, where the tag-label can be translated (multilingual). I'm currently looking at Toxi, which is a very simple and clean way of creating a tagging ...
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0answers
24 views

Code First Migrations with an existing database - How do I make sure migration won't affect the existing data?

I am referring https://docs.microsoft.com/en-us/ef/ef6/modeling/code-first/migrations/existing-database I am using Entity frame work Code First Migrations for an existing database. I get the below ...
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2answers
98 views

INNER JOIN is extremly slow on some rows and create temp table

The MySQL query SELECT `p`.*, `p.Author`.* FROM `post` AS `p` INNER JOIN `user` AS `p.Author` ON `p`.`userid` = `p.Author`.`userid` WHERE ( ( `p`.`threadid` = 29780 ) AND ( `...
3
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2answers
128 views

SQL Server one-to-many and index fragmentation

I'm currently writing code to update an entities child collection (one-to-many relationship), and while thinking about how to write code to determine which entities have been added/removed/modified, I ...
2
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2answers
102 views

Performance problem with big query on first run

I'm having a problem with a query usually being so slow on first time run that it times out and then executing in under a second once it's loaded into cache. The query looks something like this exec ...
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1answer
718 views

Can Entity Framework access In Memory OLTP Tables?

Are there any restrictions with having Entity Framework access In Memory OLTP Tables? Or is this not possible?
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1answer
64 views

Delete Joined to Derived Table Causes Index Scan and Table Spool

Our application uses a popular 3rd-party extension to Entity Framework that allows for valuable things that native Entity Framework is not capable of or designed to do, like bulk deletes and updates. ...
3
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1answer
2k views

Passing an array of integers as a parameter of an (inline) user defined function (SQL Server)

I have TBV function . Like this ALTER FUNCTION [dbo].[fn_Functiont] ( @accessibleIds ListAccesableIds READONLY ) RETURNS TABLE AS RETURN ( SELECT d.*, b.Name AS Name, ps.Name AS ...
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0answers
413 views

Keeping MySql connections alive

I'm running a Windows service, which connects to a MySql database via Entity Framework. Every 10 seconds it issues a query to the database to see if any new records have been added. If it finds any, ...
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1answer
128 views

Empty result takes longer with all columns included

I'm executing a query every 1 second and most of the time it returns no results (SQL generated by Entity Framework): SELECT TOP (5) [Extent1].[ID] AS [ID], ***30 more columns*** FROM ...
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163 views

SQL Server bitfield/flags in int indexing

In a schema, an int is used as a bitfield, one of those bits is used in a frequently called SQL query (a bit marking entries to be new for processing). The query (entity framework generated, got it ...
1
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1answer
200 views

Inserts via Entity Framework on server take about double the time than locally

I'm inserting lots of data into SQL Server with many of them having foreign key dependencies. Meaning if I insert 1 row in my Person table, I'm also inserting 1 row in 8 other related tables. This ...
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2answers
2k views

SQL Server Order SELECT List with condition

I want order the select list with condition. For example; I have t1 table and it has 3 columns and 6 rows Table t1: +----+---+---+ | id | x | y | +----+---+---+ | 1 | a | 1 | | 2 | b | 3 | | 3 |...
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1answer
234 views

My first database schema design

I'm new to programming and databases and working on my first application using .Net, Entity (for SQL Server) and Identity. My application will allow users to create html pages for online courses. ...
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1answer
344 views

sp_executesql processes uniqueidentifier-param with EntityCommandExecutionException but still acts like expected

I use a Azure DB(MS-Sql) and administrate the DB with Management Studio for SQL Server 2016. My Application is a simple C#/WPF-Application. So here we go, this is my SProc: ALTER PROCEDURE [dbo]....
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1answer
119 views

Entity Framework Coupling with Database

I am new to EF and Database Design. I have been studying about using Repository Pattern and Unit of Work a lot, and I have seen a lot of queries made with LINQ. But I have one question. If, in ...
3
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3answers
2k views

Visual Studio database project and Enity Framework code-first

At work we are developing our latest module in C# Entity framework code-first approach. I have been given the role of developing databases from the DBContexts from within the project/s. I generated ...
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1answer
424 views

Parent / Child relation appears to insert out of order via EntityFramework

I'm facing a peculiar issue, when the following code completes, and using (var db = new DbContext()) { var msReceived = new MilestonesReceived() { ...
2
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1answer
113 views

DB Design Challenge

I don't have much experience designing databases and I have this case that I stumbled upon where I hope there is a definite answer in terms of DB design methodologies. I also have to mention that I am ...
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2answers
203 views

Custom Paging in Stored Procedure (Optimizing the Performance)

I have a stored procedure that is working perfectly but the issue is performance. There are so many joins in this stored procedure and unions... So after having the query executed, i need to send only ...
1
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1answer
340 views

Unnecessary Hash Match in Query

I've just migrated a database from SQLExpress (Entity, Database First) to Azure (Entity, Code First) and some of the indexes are missing because they werent migrated (on purpose, I think a lot of them ...
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1answer
211 views

Inheritance and performance in database [closed]

I have 3 table linked by an "inheritance" with Entity Framework. Sadly, I have poor performance with those query because I can't make any good index. Here is the tables : CREATE TABLE [dbo].[...
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1answer
755 views

Create a User and Password for ADO.net and SQL SERVER Authentication

I am trying to create a sample application in asp .net mvc with sql server authentication. I want to create a user with password in sql server so that i can provide it in connection string in asp ....
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2answers
2k views

What's the best practice of inserting a collection of data into a SQL Server database

I am using C#, Entity Framework. SQL Server for the development. I have a method which has two parameters (int ID, List<String> _listobj). For each ID, there is a list of obj. All of these IDs ...
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1answer
362 views

Data read from linked server returns different data-type on production server

I have a SQL Server grabbing data from a linked Oracle server inside a SP. On my development server, EF6 insists the SP is returning a double datatype for one of the columns, but in prod, it insists ...
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1answer
128 views

The same set of columns for two tables

I have the following db schemas: Comments table and Posts table ( has FK to Comments table) : As you can see, there is a set of the same columns for both tables. Is it bad design? If yes, how can ...
3
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1answer
70 views

Complex dto based result sets with EF and MS SQL server

ok lets say I have a collection of these ... public class ReferenceLookup { public string InvoiceNumber { get; set; } public CompanyReference Buyer { get; set; } public CompanyReference ...
3
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1answer
3k views

Entity Framework SaveChanges fails due to a trigger

Trying to implement Entity Framework for an existing database (SQL Server 2012). I have a VB application running and trying to convert it to the EF based Web API. When I insert data into the table ...
2
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1answer
225 views

best way to add Entity id & entity types in database

we are doing shopping site with mysql with eav model to store values. in below image , 2 types of entity types are there under products_information table : 1) Mobile 2) T-shirts I wanted to know in ...
2
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1answer
2k views

Handle concurrency on sql server for a booking system

I've been banging my head against the wall trying to solve this problem and I couldn't come up with a solution that absolutely guarantees two users can't book an appointment for the same time. The ...
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2answers
2k views

Why shouldn't I increase SQL Server's timeout globally everywhere?

I have an application in which some reports time out before getting data. We started increasing timeout througout our code in different places, and as our database is growing bigger and bigger, we see ...
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1answer
28 views

Remove some auto created indices from Entity Framework?

I'm using Microsoft's Entity Framework. It automatically creates indices for every foreign key, but in many cases, I can see from the index stats that these are never used for reading - they are only ...
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1answer
2k views

Very slow insert performance on large table (EF) [closed]

One of our systems has a table that receives around 20k inserts per day - it currently contains ~10m rows. We've just pushed out a system upgrade and I'm intermittently getting some shockingly slow ...
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0answers
348 views

Help with SSIS Framework- Resolve Referrences in Data Flow

LineageString and StageKey are both unmapped. SSIS is giving me an error between the OLE DB Source and the Add metadata. Add Metadata.Inputs[Derived Column Input].Columns[LineageString] has lineage ...
3
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2answers
717 views

Table with only a single constant value?

I use C# entity framework code first. My knowledge regarding databases is almost nothing. I don't know if it's common or good practice so I wanted to ask you guys how I should do it. Say I have a ...
6
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2answers
596 views

SQL server Database statistics degrading after execution

I have been experiencing timeouts while querying my SQL Server DB in particular one table. I tried updating the statistics and it fixed the performance issues for a couple of days. I started digging ...
4
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0answers
168 views

Azure SQL DB migration from Visual Studio raises collation error

I want to run a migration in my Azure hosted database. The migration works perfect in several local machines. When I try targeting the Azure database it raises the following exception: Column X is ...
2
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0answers
130 views

Splitting very large working table

I read the good posts here and here, but my scenario is a bit different, I cannot consider that older data becomes read-only data because any record in my Transactions table can be subject to updates ...
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1answer
5k views

Entity Framework C#: Get rows between two dates [closed]

I have an SQL server database with a column named "Time" of format "datetime". In C# Entity Framework, I want to get all rows whose date is after 8am of today: using (var db = new ...
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1answer
77 views

How to return the difference (columns) between two databases or tables

I have a database that has been updated, many columns have been added. Currently the only way of returning the differences between the two databases is by going through the database.cs class that is ...
0
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1answer
32 views

Foreign key not able to get one to many working

I want to have a one to many relation with player points but I need it in such a way that entity framework sees it as a collection so i can add to it. I mean that one player can have multiple points ...
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1answer
19 views

Entity or attribute if only one field beside key and attribute for other entity?

Let's say I have an entity person which has an attribute Email. But the person can have more than one Email address. So I have to put this attribute into a separate table. But what I do not ...
3
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1answer
3k views

Encryption/Decryption with stored procedure / view

I'm working on a project that uses Entity Framework for programmers to access the data. We've recently found need to add fields that were determined that need to be encrypted. This will be the first ...
2
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2answers
117 views

One table or duplicate table with same properties but different dependencies

Disclaimer: I'm new to database modeling so I apologize in advance if the question is unclear or causes any confusion. I am using .NET Entity Framework and have the following tables: An Order can ...
0
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1answer
818 views

Database structure for object with dynamic attributes

I am developing a proof of concept for a personalized email sending web application (like MailChimp, but with premade dynamic templates). The general structure is that I have my templates (different ...
9
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2answers
7k views

Why do async_network_io wait types occur?

Last week something strange happened on our database. All of a sudden, the application blocked for our users who were not able to save new entities etc. After looking at the Activity Monitor of the ...
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2answers
1k views

SQL server avoid procedures parameter sniffing

I'm getting slow performances from this procedure CREATE PROCEDURE MyProcedure01 @date datetime2(7) AS BEGIN SELECT [Limit1].[C2] AS [C1], [Limit1].[mc_object] AS [mc_object], [Limit1].[C1] ...
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2answers
80 views

Referencing a single table from all tables in the database

At current, I have around 130 tables in my database, anticipating a growth of circa 200 tables in total. Now I have several tables (well, most of them, actually) that contain properties like ...
2
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1answer
263 views

Can I grant multiple remote LocalService accounts access to a SQL Server database?

I am designing a multi-environment Windows-based software product that will extensively employ Windows services running as LocalService to perform data access operations. All of the data access ...