entity-framework-5

Calculated column in EF Code First

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You can create computed columns in your database tables. In the EF model you just annotate the corresponding properties with the DatabaseGenerated attribute: [DatabaseGenerated(DatabaseGeneratedOption.Computed)] public double Summ { get; private set; } Or with fluent mapping: modelBuilder.Entity<Income>().Property(t => t.Summ) .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Computed) As suggested by Matija Grcic and in a comment, it’s a good idea to make … Read more

How to “warm-up” Entity Framework? When does it get “cold”?

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What would be the best approach to have high availability on my Entity Framework at anytime? You can go for a mix of pregenerated views and static compiled queries. Static CompiledQuerys are good because they’re quick and easy to write and help increase performance. However with EF5 it isn’t necessary to compile all your queries … Read more

Could not load file or assembly Microsoft.SqlServer.management.sdk.sfc version 11.0.0.0

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Problem: (Sql server 2014) This issue happens when assembly Microsoft.SqlServer.management.sdk.sfc version 12.0.0.0 not found by visual studio. Solution: just go to http://www.microsoft.com/en-us/download/details.aspx?id=42295 and download: ENU\x64\SharedManagementObjects.msi for X64 OS or ENU\x86\SharedManagementObjects.msi for X86 OS, then install it, and restart visual studio. PS: You may need install DB2OLEDBV5_x64.msi or DB2OLEDBV5_x86.msi too. Problem: (Sql server 2012) This issue … Read more

How do I enable EF migrations for multiple contexts to separate databases?

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The 2nd call to Enable-Migrations is failing because the Configuration.cs file already exists. If you rename that class and file, you should be able to run that 2nd Enable-Migrations, which will create another Configuration.cs. You will then need to specify which configuration you want to use when updating the databases. Update-Database -ConfigurationTypeName MyRenamedConfiguration

EF5: Cannot attach the file ‘{0}’ as database ‘{1}’

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If you delete the DB file, it still stays registered with SqlLocalDB. Sometimes it fixes it to delete the DB. You can do this from the command line. Open the “Developer Command Propmpt for VisualStudio” under your start/programs menu. Run the following commands: sqllocaldb.exe stop v11.0 sqllocaldb.exe delete v11.0

Debug code-first Entity Framework migration codes

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I know that EF Code First Migrations is relatively new tool but don’t forget about you are still in .NET. So you can use: if (System.Diagnostics.Debugger.IsAttached == false) { System.Diagnostics.Debugger.Launch(); } After that you can see your InnerException. Or you can use try…catch statement like this: Exception handling Entity Framework

Entity Framework Migrations renaming tables and columns

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Nevermind. I was making this way more complicated than it really needed to be. This was all that I needed. The rename methods just generate a call to the sp_rename system stored procedure and I guess that took care of everything, including the foreign keys with the new column name. public override void Up() { … Read more

Entity Framework Join 3 Tables

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I think it will be easier using syntax-based query: var entryPoint = (from ep in dbContext.tbl_EntryPoint join e in dbContext.tbl_Entry on ep.EID equals e.EID join t in dbContext.tbl_Title on e.TID equals t.TID where e.OwnerID == user.UID select new { UID = e.OwnerID, TID = e.TID, Title = t.Title, EID = e.EID }).Take(10); And you should … Read more

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)