var members = context.Members
                                    .Select(member => new { Name = member.Surname + ", " + member.FirstName })
                                    .ToList();

var facilities = context.Facilities
                                        .Where(facility => facility.Name.StartsWith("Tennis"))
                                        .ToList();

var members = context.Members
                                    .Select(member => new { member.MemId, member.Telephone })
                                    .Where(member => member.Telephone.Contains("(")
                                                    && member.Telephone.Contains(")"))
                                    .ToList();

members = context.Members
                                    .Select(member => new { member.MemId, member.Telephone })
                                    .Where(member => EF.Functions.Like(member.Telephone, "%[()]%"))
                                    .ToList();

SELECT   CONVERT (NVARCHAR (MAX), [m].[ZipCode]) AS [Zip]
FROM     [Members] AS [m]
ORDER BY CONVERT (NVARCHAR (MAX), [m].[ZipCode]);

var members = context.Members
                                    .Select(member => new { ZipCode = Convert.ToString(member.ZipCode) })
                                    .OrderBy(m => m.ZipCode)
                                    .ToList();
// Now using LINQ to Objects
members = members.Select(member => new { ZipCode = member.ZipCode.PadLeft(5, '0') })
                                                    .OrderBy(m => m.ZipCode)
                                                    .ToList();

namespace EFCorePgExercises.Utils
{
    public static class SqlDbFunctionsExtensions
    {
        public static string SqlReplicate(string expression, int count)
            => throw new InvalidOperationException($"{nameof(SqlReplicate)} method cannot be called from the client side.");

        private static readonly MethodInfo _sqlReplicateMethodInfo = typeof(SqlDbFunctionsExtensions)
            .GetRuntimeMethod(
                nameof(SqlDbFunctionsExtensions.SqlReplicate),
                new[] { typeof(string), typeof(int) }
            );


        public static void AddCustomSqlFunctions(this ModelBuilder modelBuilder)
        {
            modelBuilder.HasDbFunction(_sqlReplicateMethodInfo)
                .HasTranslation(args =>
                {
                    return SqlFunctionExpression.Create("REPLICATE",
                        args,
                        _sqlReplicateMethodInfo.ReturnType,
                        typeMapping: null);
                });
        }
    }
}

namespace EFCorePgExercises.DataLayer
{
    public class ApplicationDbContext : DbContext
    {
         // ...

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
         // ...
            modelBuilder.AddCustomSqlFunctions();
         // ...
        }
    }
}

var newMembers = context.Members
                                        .Select(member => new
                                        {
                                            ZipCode =
                                                SqlDbFunctionsExtensions.SqlReplicate(
                                                    "0", 5 - Convert.ToString(member.ZipCode).Length)
                                                + member.ZipCode
                                        })
                        .OrderBy(m => m.ZipCode)
                        .ToList();

var members = context.Members
                                    .Select(member => new { Letter = member.Surname.Substring(0, 1) })
                                    .GroupBy(m => m.Letter)
                                    .Select(g => new
                                    {
                                        Letter = g.Key,
                                        Count = g.Count()
                                    })
                                    .OrderBy(r => r.Letter)
                                    .ToList();

select memid, regexp_replace(telephone, '[^0-9]', '', 'g') as telephone
from members
order by memid;

var members = context.Members
                                .Select(member => new
                                {
                                    member.MemId,
                                    Telephone = member.Telephone.Replace("-", "")
                                                        .Replace("(", "")
                                                        .Replace(")", "")
                                                        .Replace(" ", "")
                                })
                                .OrderBy(r => r.MemId)
                                .ToList();

    public class Bill
    {
        public int Id { set; get; }
        public string Name { set; get; }

        public virtual ICollection<Transaction> Transactions { set; get; }
    }

    public class Transaction
    {
        public int Id { set; get; }
        public DateTime AddDate { set; get; }
        public int Amount { set; get; }

        [ForeignKey("BillId")]
        public virtual Bill Bill { set; get; }
        public int BillId { set; get; }
    }

    public class MyContext : DbContext
    {
        public DbSet<Bill> Bills { get; set; }
        public DbSet<Transaction> Transactions { get; set; }
    }

    public class Configuration : DbMigrationsConfiguration<MyContext>
    {
        public Configuration()
        {
            AutomaticMigrationsEnabled = true;
            AutomaticMigrationDataLossAllowed = true;
        }

        protected override void Seed(MyContext context)
        {
            var bill1 = new Bill { Name = "bill-1" };
            context.Bills.Add(bill1);

            for (int i = 0; i < 11; i++)
            {
                context.Transactions.Add(new Transaction
                {
                    AddDate = DateTime.Now.AddDays(-i),
                    Amount = 1000000000 + i,
                    Bill = bill1
                });
            }
            base.Seed(context);
        }
    }

    public static class Test
    {
        public static void RunTests()
        {
            Database.SetInitializer(new MigrateDatabaseToLatestVersion<MyContext, Configuration>());
            using (var context = new MyContext())
            {
                var sum = context.Transactions.Sum(x => x.Amount);
                Console.WriteLine(sum);
            }
        }
    }

SELECT 
         [GroupBy1].[A1] AS [C1]
         FROM ( SELECT 
                    SUM([Extent1].[Amount]) AS [A1]
                    FROM [dbo].[Transactions] AS [Extent1]
                    )  AS [GroupBy1]

 Arithmetic overflow error converting expression to data type int.

var sum2 = context.Transactions.Sum(x => (Int64)x.Amount);

SELECT 
      [GroupBy1].[A1] AS [C1]
         FROM ( SELECT 
                    SUM( CAST( [Extent1].[Amount] AS bigint)) AS [A1]
                    FROM [dbo].[Transactions] AS [Extent1]
               )  AS [GroupBy1]                  

var date = DateTime.Now.AddDays(10);
var sum3 = context.Transactions
                  .Where(x => x.AddDate > date)  
                  .Sum(x => (Int64)x.Amount);               

SELECT 
     [GroupBy1].[A1] AS [C1]
        FROM ( SELECT 
                    SUM( CAST( [Extent1].[Amount] AS bigint)) AS [A1]
                    FROM [dbo].[Transactions] AS [Extent1]
                    WHERE [Extent1].[AddDate] > @p__linq__0
              )  AS [GroupBy1]

The cast to value type 'Int64' failed because the materialized value is null.
Either the result type's generic parameter or the query must use a nullable type.

var date = DateTime.Now.AddDays(10);
var sum3 = context.Transactions
                  .Where(x => x.AddDate > date)
                  .Sum(x => (Int64?)x.Amount) ?? 0;

 var sum4 = context.Bills.First().Transactions.Sum(x => (Int64?)x.Amount) ?? 0;

SELECT 
     [Extent1].[Id] AS [Id], 
     [Extent1].[AddDate] AS [AddDate], 
     [Extent1].[Amount] AS [Amount], 
     [Extent1].[BillId] AS [BillId]
   FROM [dbo].[Transactions] AS [Extent1]
   WHERE [Extent1].[BillId] = @EntityKeyValue1

var entry = context.Bills.First();
var sum5 = context.Entry(entry).Collection(x => x.Transactions).Query().Sum(x => (Int64?)x.Amount) ?? 0;

SELECT 
    [GroupBy1].[A1] AS [C1]
     FROM ( SELECT 
               SUM( CAST( [Extent1].[Amount] AS bigint)) AS [A1]
                   FROM [dbo].[Transactions] AS [Extent1]
                    WHERE [Extent1].[BillId] = @EntityKeyValue1
            )  AS [GroupBy1]                  

  <connectionStrings>
    <clear />
    <add name="Sample07Context" connectionString="Data Source=(local);Initial Catalog=TestDbIoC;Integrated Security = true" providerName="System.Data.SqlClient" />
    <add name="Database2012" connectionString="Data Source=(local);Initial Catalog=testdb2012;Integrated Security = true" providerName="System.Data.SqlClient" />
  </connectionStrings>

using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using EF_Sample07.DomainClasses;
 
namespace EF_Sample07.DataLayer.Context
{
    public class Sample07Context : DbContext, IUnitOfWork
    {
        public DbSet<Category> Categories { set; get; }
        public DbSet<Product> Products { set; get; }
 
        /// <summary>
        /// It looks for a connection string named Sample07Context in the web.config file.
        /// </summary>
        public Sample07Context()
            : base("Sample07Context")
        {
        }
 
        /// <summary>
        /// To change the connection string at runtime. See the SmObjectFactory class for more info.
        /// </summary>
        public Sample07Context(string connectionString)
            : base(connectionString)
        {
            //Note: defaultConnectionFactory in the web.config file should be set.
        }
 
 
        public void SetConnectionString(string connectionString)
        {
            this.Database.Connection.ConnectionString = connectionString;
        }
    }
}

using System;
using System.Threading;
using System.Web;
using EF_Sample07.DataLayer.Context;
using EF_Sample07.ServiceLayer;
using StructureMap;
using StructureMap.Web;
using StructureMap.Web.Pipeline;
 
namespace EF_Sample07.IoCConfig
{
    public static class SmObjectFactory
    {
        private static readonly Lazy<Container> _containerBuilder =
            new Lazy<Container>(defaultContainer, LazyThreadSafetyMode.ExecutionAndPublication);
 
        public static IContainer Container
        {
            get { return _containerBuilder.Value; }
        }
 
        public static void HttpContextDisposeAndClearAll()
        {
            HttpContextLifecycle.DisposeAndClearAll();
        }
 
        private static Container defaultContainer()
        {
            return new Container(ioc =>
            {
                // session manager setup
                ioc.For<ISessionProvider>().Use<DefaultWebSessionProvider>();
                ioc.For<HttpSessionStateBase>()
                   .Use(ctx => new HttpSessionStateWrapper(HttpContext.Current.Session));
 
                ioc.For<IUnitOfWork>()
                   .HybridHttpOrThreadLocalScoped()
                   .Use<Sample07Context>()
                    // Remove these 2 lines if you want to use a connection string named Sample07Context, defined in the web.config file.
                   .Ctor<string>("connectionString")
                   .Is(ctx => getCurrentConnectionString(ctx));
 
                ioc.For<ICategoryService>().Use<EfCategoryService>();
                ioc.For<IProductService>().Use<EfProductService>();
 
                ioc.For<ICategoryService>().Use<EfCategoryService>();
                ioc.For<IProductService>().Use<EfProductService>();
 
                ioc.Policies.SetAllProperties(properties =>
                {
                    properties.OfType<IUnitOfWork>();
                    properties.OfType<ICategoryService>();
                    properties.OfType<IProductService>();
                    properties.OfType<ISessionProvider>();
                });
            });
        }
 
        private static string getCurrentConnectionString(IContext ctx)
        {
            if (HttpContext.Current != null)
            {
                // this is a web application
                var sessionProvider = ctx.GetInstance<ISessionProvider>();
                var connectionString = sessionProvider.Get<string>("CurrentConnectionString");
                if (string.IsNullOrWhiteSpace(connectionString))
                {
                    // It's a default connectionString.
                    connectionString = "Database2012";
                    // this session value should be set during the login phase
                    sessionProvider.Store("CurrentConnectionStringName", connectionString);
                }
 
                return connectionString;
            }
            else
            {
                // this is a desktop application, so you can store this value in a global static variable.
                return "Database2012";
            }
        }
    }
}

 sessionProvider.Store("CurrentConnectionString", "Sample07Context");
uow.SetConnectionString(WebConfigurationManager.ConnectionStrings[_sessionProvider.Get<string>("CurrentConnectionString")].ConnectionString);

using System;
using System.Data.Entity;
using System.Web;
using EF_Sample07.DataLayer.Context;
using EF_Sample07.IoCConfig;
 
namespace EF_Sample07.WebFormsAppSample
{
    public class Global : HttpApplication
    {
        void Application_Start(object sender, EventArgs e)
        {
            initDatabases();
        }
 
        private static void initDatabases()
        {
            // defined in web.config
            string[] connectionStringNames =
            {
                "Sample07Context",
                "Database2012"
            };
 
            foreach (var connectionStringName in connectionStringNames)
            {
                Database.SetInitializer(
                    new MigrateDatabaseToLatestVersion<Sample07Context, Configuration>(connectionStringName));
 
                using (var ctx = new Sample07Context(connectionStringName))
                {
                    ctx.Database.Initialize(force: true);
                }
            }
        }
 
        void Application_EndRequest(object sender, EventArgs e)
        {
            SmObjectFactory.HttpContextDisposeAndClearAll();
        } 
    }
}

optionsBuilder.UseSqlServer(
   @"Server=(localdb)\mssqllocaldb;Database=Demo.Batching;Trusted_Connection=True;",
   options => options.MaxBatchSize(1)
);

public class SqlServerModificationCommandBatch : AffectedCountModificationCommandBatch
    {
        private const int DefaultNetworkPacketSizeBytes = 4096;
        private const int MaxScriptLength = 65536 * DefaultNetworkPacketSizeBytes / 2;
        private const int MaxParameterCount = 2100;
        private const int MaxRowCount = 1000;

    public class Blog
    {
        public int BlogId { get; set; }
        public string Name { get; set; }
        public string Url { get; set; }
    }

    public class BloggingContext : DbContext
    {
        public DbSet<Blog> Blogs { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer(
                @"Server=(localdb)\mssqllocaldb;Database=Demo.Batching;Trusted_Connection=True;"/*,
                options => options.MaxBatchSize(2)*/
                );
            optionsBuilder.EnableSensitiveDataLogging();
        }
    }

            using (var db = new BloggingContext())
            {
                db.GetService<ILoggerFactory>().AddProvider(new MyLoggerProvider());

                // Modify some existing blogs
                var existing = db.Blogs.ToArray();
                existing[0].Url = "http://sample.com/blogs/dogs";
                existing[1].Url = "http://sample.com/blogs/cats";

                // Insert some new blogs
                db.Blogs.Add(new Blog { Name = "The Horse Blog", Url = "http://sample.com/blogs/horses" });
                db.Blogs.Add(new Blog { Name = "The Snake Blog", Url = "http://sample.com/blogs/snakes" });
                db.Blogs.Add(new Blog { Name = "The Fish Blog", Url = "http://sample.com/blogs/fish" });
                db.Blogs.Add(new Blog { Name = "The Koala Blog", Url = "http://sample.com/blogs/koalas" });
                db.Blogs.Add(new Blog { Name = "The Parrot Blog", Url = "http://sample.com/blogs/parrots" });
                db.Blogs.Add(new Blog { Name = "The Kangaroo Blog", Url = "http://sample.com/blogs/kangaroos" });

                db.SaveChanges();
            }

Executed DbCommand (41ms) [Parameters=[@p1='57', @p0='http://sample.com/blogs/dogs' (Size = 4000), @p3='58', @p2='http://sample.com/blogs/cats' (Size = 4000), @p4='The Horse Blog' (Size = 4000), @p5='http://sample.com/blogs/horses' (Size = 4000), @p6='The Snake Blog' (Size = 4000), @p7='http://sample.com/blogs/snakes' (Size = 4000), @p8='The Fish Blog' (Size = 4000), @p9='http://sample.com/blogs/fish' (Size = 4000), @p10='The Koala Blog' (Size = 4000), @p11='http://sample.com/blogs/koalas' (Size = 4000), @p12='The Parrot Blog' (Size = 4000), @p13='http://sample.com/blogs/parrots' (Size = 4000), @p14='The Kangaroo Blog' (Size = 4000), @p15='http://sample.com/blogs/kangaroos' (Size = 4000)], CommandType='Text', CommandTimeout='30']
SET NOCOUNT ON;
UPDATE [Blogs] SET [Url] = @p0
WHERE [BlogId] = @p1;
SELECT @@ROWCOUNT;

UPDATE [Blogs] SET [Url] = @p2
WHERE [BlogId] = @p3;
SELECT @@ROWCOUNT;

DECLARE @inserted2 TABLE ([BlogId] int, [_Position] [int]);
MERGE [Blogs] USING (
VALUES (@p4, @p5, 0),
(@p6, @p7, 1),
(@p8, @p9, 2),
(@p10, @p11, 3),
(@p12, @p13, 4),
(@p14, @p15, 5)) AS i ([Name], [Url], _Position) ON 1=0
WHEN NOT MATCHED THEN
INSERT ([Name], [Url])
VALUES (i.[Name], i.[Url])
OUTPUT INSERTED.[BlogId], i._Position
INTO @inserted2;

SELECT [t].[BlogId] FROM [Blogs] t
INNER JOIN @inserted2 i ON ([t].[BlogId] = [i].[BlogId])
ORDER BY [i].[_Position];

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
   optionsBuilder.UseSqlServer(
     @"Server=(localdb)\mssqllocaldb;Database=Demo.Batching;Trusted_Connection=True;",
     options => options.MaxBatchSize(2)
    );
    optionsBuilder.EnableSensitiveDataLogging();
}

Executed DbCommand (17ms) [Parameters=[@p1='65', @p0='http://sample.com/blogs/dogs' (Size = 4000), @p3='66', @p2='http://sample.com/blogs/cats' (Size = 4000)], CommandType='Text', CommandTimeout='30']
SET NOCOUNT ON;
UPDATE [Blogs] SET [Url] = @p0
WHERE [BlogId] = @p1;
SELECT @@ROWCOUNT;

UPDATE [Blogs] SET [Url] = @p2
WHERE [BlogId] = @p3;
SELECT @@ROWCOUNT;

Executed DbCommand (18ms) [Parameters=[@p0='The Horse Blog' (Size = 4000), @p1='http://sample.com/blogs/horses' (Size = 4000), @p2='The Snake Blog' (Size = 4000), @p3='http://sample.com/blogs/snakes' (Size = 4000)], CommandType='Text', CommandTimeout='30']
SET NOCOUNT ON;
DECLARE @inserted0 TABLE ([BlogId] int, [_Position] [int]);
MERGE [Blogs] USING (
VALUES (@p0, @p1, 0),
(@p2, @p3, 1)) AS i ([Name], [Url], _Position) ON 1=0
WHEN NOT MATCHED THEN
INSERT ([Name], [Url])
VALUES (i.[Name], i.[Url])
OUTPUT INSERTED.[BlogId], i._Position
INTO @inserted0;

SELECT [t].[BlogId] FROM [Blogs] t
INNER JOIN @inserted0 i ON ([t].[BlogId] = [i].[BlogId])
ORDER BY [i].[_Position];

Executed DbCommand (34ms) [Parameters=[@p0='The Fish Blog' (Size = 4000), @p1='http://sample.com/blogs/fish' (Size = 4000), @p2='The Koala Blog' (Size = 4000), @p3='http://sample.com/blogs/koalas' (Size = 4000)], CommandType='Text', CommandTimeout='30']
SET NOCOUNT ON;
DECLARE @inserted0 TABLE ([BlogId] int, [_Position] [int]);
MERGE [Blogs] USING (
VALUES (@p0, @p1, 0),
(@p2, @p3, 1)) AS i ([Name], [Url], _Position) ON 1=0
WHEN NOT MATCHED THEN
INSERT ([Name], [Url])
VALUES (i.[Name], i.[Url])
OUTPUT INSERTED.[BlogId], i._Position
INTO @inserted0;

SELECT [t].[BlogId] FROM [Blogs] t
INNER JOIN @inserted0 i ON ([t].[BlogId] = [i].[BlogId])
ORDER BY [i].[_Position];

Executed DbCommand (15ms) [Parameters=[@p0='The Parrot Blog' (Size = 4000), @p1='http://sample.com/blogs/parrots' (Size = 4000), @p2='The Kangaroo Blog' (Size = 4000), @p3='http://sample.com/blogs/kangaroos' (Size = 4000)], CommandType='Text', CommandTimeout='30']
SET NOCOUNT ON;
DECLARE @inserted0 TABLE ([BlogId] int, [_Position] [int]);
MERGE [Blogs] USING (
VALUES (@p0, @p1, 0),
(@p2, @p3, 1)) AS i ([Name], [Url], _Position) ON 1=0
WHEN NOT MATCHED THEN
INSERT ([Name], [Url])
VALUES (i.[Name], i.[Url])
OUTPUT INSERTED.[BlogId], i._Position
INTO @inserted0;

SELECT [t].[BlogId] FROM [Blogs] t
INNER JOIN @inserted0 i ON ([t].[BlogId] = [i].[BlogId])
ORDER BY [i].[_Position];

 try {
     int i=0;
     string s = "hello";
     i = Convert.ToInt32(s);
} catch (Exception ex)
{
     Console.WriteLine("Error");
}
Console.WriteLine("I am here!");

  public static int GetMyInt()
 {
     try {
          for (int i=10;i>=0;i--)
             Console.WriteLine(10/i);
         return 1;
     } catch
     {
         Console.WriteLine("Error!");
     }
     finally {
         Console.WriteLine("ok");
     }
     Console.WriteLine("can you reach here?");  
     return -1;  
 }

public static int GetMyInt()
 {
     try {
          for (int i=10;i>=1;i--)
             Console.WriteLine(10/i);
         return 1;
     } catch
     {
         Console.WriteLine("Error!");
     }
     finally {
         Console.WriteLine("ok");
     }
     Console.WriteLine("can you reach here?");  
     return -1;  
 }