Use a unique identifier for variables during insert

FIxes #26632

All.sln

@@ -2,7 +2,7 @@
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
 VisualStudioVersion = 17.0.31521.260
-MinimumVisualStudioVersion = 16.0.28418.106
+MinimumVisualStudioVersion = 17.0.31521.260
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{B9E4CC99-199C-4E3B-9EC5-D1FDFCD6C27B}"
 	ProjectSection(SolutionItems) = preProject
 		.editorconfig = .editorconfig

src/EFCore.SqlServer/Update/Internal/SqlServerUpdateSqlGenerator.cs

@@ -65,7 +65,7 @@ public virtual ResultSetMapping AppendBulkInsertOperation(
                         modificationCommands[0],
                         modificationCommands[0].ColumnModifications.Where(o => o.IsKey).ToList(),
                         modificationCommands[0].ColumnModifications.Where(o => o.IsRead).ToList(),
-                        0);
+                        commandPosition);
             }
 
             var readOperations = modificationCommands[0].ColumnModifications.Where(o => o.IsRead).ToList();

test/EFCore.SqlServer.FunctionalTests/SqlServerEndToEndTest.cs

@@ -8,6 +8,7 @@
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore.Metadata;
 using Microsoft.EntityFrameworkCore.TestUtilities;
 using Xunit;
 
@@ -873,6 +874,193 @@ public void Can_replace_identifying_FK_entity_with_many_to_many()
             }
         }
 
+        [ConditionalTheory]
+        [MemberData(
+            nameof(DataGenerator.GetCombinations),
+            new object[] { 0, 1, 2, 3, 4 },
+            2,
+            MemberType = typeof(DataGenerator))]
+        public void Can_insert_entities_with_generated_PKs(int studentCount, int courseCount)
+        {
+            var students = new Student[]
+            {
+                new Student{FirstMidName="Carson",LastName="Alexander",EnrollmentDate=DateTime.Parse("2019-09-01")},
+                new Student{FirstMidName="Meredith",LastName="Alonso",EnrollmentDate=DateTime.Parse("2017-09-01")},
+                new Student{FirstMidName="Arturo",LastName="Anand",EnrollmentDate=DateTime.Parse("2018-09-01")},
+                new Student{FirstMidName="Gytis",LastName="Barzdukas",EnrollmentDate=DateTime.Parse("2017-09-01")},
+                new Student{FirstMidName="Yan",LastName="Li",EnrollmentDate=DateTime.Parse("2017-09-01")},
+                new Student{FirstMidName="Peggy",LastName="Justice",EnrollmentDate=DateTime.Parse("2016-09-01")},
+                new Student{FirstMidName="Laura",LastName="Norman",EnrollmentDate=DateTime.Parse("2018-09-01")},
+                new Student{FirstMidName="Nino",LastName="Olivetto",EnrollmentDate=DateTime.Parse("2019-09-01")}
+            };
+
+            var courses = new Course[]
+            {
+                new Course{Title="Chemistry",Credits=3},
+                new Course{Title="Microeconomics",Credits=3},
+                new Course{Title="Macroeconomics",Credits=3},
+                new Course{Title="Calculus",Credits=4},
+                new Course{Title="Trigonometry",Credits=4},
+                new Course{Title="Composition",Credits=3},
+                new Course{Title="Literature",Credits=4}
+            };
+
+            using var testDatabase = SqlServerTestStore.CreateInitialized(DatabaseName);
+            var options = Fixture.CreateOptions(testDatabase);
+
+            using (var context = new UniversityContext(options))
+            {
+                context.Database.EnsureCreatedResiliently();
+                for (var i = 0; i < studentCount; i++)
+                {
+                    context.Students.Add(students[i]);
+                }
+                for (var i = 0; i < courseCount; i++)
+                {
+                    context.Courses.Add(courses[i]);
+                }
+
+                context.SaveChanges();
+            }
+
+            using (var context = new UniversityContext(options))
+            {
+                Assert.Equal(studentCount, context.Students.Count());
+                Assert.Equal(courseCount, context.Courses.Count());
+            }
+        }
+
+        public class Course
+        {
+            public Guid Id { get; set; }
+
+            public string Title { get; set; } = string.Empty;
+
+            public int Credits { get; set; }
+
+            public virtual ICollection<Enrollment> Enrollments { get; set; } = new List<Enrollment>();
+
+            public byte[] RowVersion { get; set; } = Array.Empty<byte>();
+        }
+
+        public class Student
+        {
+            public Guid Id { get; set; }
+
+            public string LastName { get; set; } = string.Empty;
+
+            public string FirstMidName { get; set; } = string.Empty;
+
+            public DateTime EnrollmentDate { get; set; }
+
+            public virtual ICollection<Enrollment> Enrollments { get; } = new List<Enrollment>();
+
+            public byte[] RowVersion { get; set; } = Array.Empty<byte>();
+        }
+
+        public enum Grade
+        {
+            A, B, C, D, F
+        }
+
+        public class Enrollment
+        {
+            public Guid Id { get; set; }
+
+            public Guid CourseId { get; set; }
+
+            public Guid StudentId { get; set; }
+
+            public Grade? Grade { get; set; }
+
+            public virtual Course Course { get; set; } = new();
+
+            public virtual Student Student { get; set; } = new();
+
+            public byte[] RowVersion { get; set; } = Array.Empty<byte>();
+        }
+
+        private class UniversityContext : DbContext
+        {
+            public UniversityContext(DbContextOptions options)
+                : base(options)
+            {
+            }
+
+            public DbSet<Student> Students { get; set; }
+            public DbSet<Course> Courses { get; set; }
+            public DbSet<Enrollment> Enrollments { get; set; }
+
+            protected override void OnModelCreating(ModelBuilder modelBuilder)
+            {
+                modelBuilder.Entity<Course>(builder =>
+                {
+                    builder.ToTable("Courses");
+
+                    builder.HasKey(x => x.Id);
+
+                    builder.Property(x => x.Id)
+                        .ValueGeneratedOnAdd()
+                        .HasDefaultValueSql("NEWSEQUENTIALID()");
+
+                    builder.Property(x => x.Title)
+                        .IsRequired()
+                        .HasMaxLength(50);
+
+                    builder.Property(x => x.RowVersion)
+                        .IsRowVersion();
+                });
+
+                modelBuilder.Entity<Student>(builder =>
+                {
+                    builder.ToTable("Students");
+
+                    builder.HasKey(x => x.Id);
+
+                    builder.Property(x => x.Id)
+                        .ValueGeneratedOnAdd()
+                        .HasDefaultValueSql("NEWSEQUENTIALID()");
+
+                    builder.Property(x => x.LastName)
+                        .IsRequired()
+                        .HasMaxLength(50);
+
+                    builder.Property(x => x.FirstMidName)
+                        .IsRequired()
+                        .HasMaxLength(50);
+
+                    builder.Property(x => x.RowVersion)
+                        .IsRowVersion();
+                });
+
+                modelBuilder.Entity<Enrollment>(builder =>
+                {
+                    builder.ToTable("Enrollments");
+
+                    builder.HasKey(x => x.Id);
+
+                    builder.Property(x => x.Id)
+                        .ValueGeneratedOnAdd()
+                        .HasDefaultValueSql("NEWSEQUENTIALID()");
+
+                    builder.Property(x => x.RowVersion)
+                        .IsRowVersion();
+
+                    builder.HasOne(t => t.Course)
+                        .WithMany(t => t.Enrollments)
+                        .HasPrincipalKey(d => d.Id)
+                        .HasForeignKey(d => d.CourseId)
+                        .OnDelete(DeleteBehavior.Cascade);
+
+                    builder.HasOne(t => t.Student)
+                        .WithMany(t => t.Enrollments)
+                        .HasPrincipalKey(d => d.Id)
+                        .HasForeignKey(d => d.StudentId)
+                        .OnDelete(DeleteBehavior.Cascade);
+                });
+            }
+        }
+
         private class EntityA
         {
             public int Id { get; set; }