unique key in entity frameworkcore code first code example
Example 1: ef code first unique constraint
[Index("IX_First", IsUnique = true)]
public int FirstColumn { get; set; }
[Index("IX_FirstAndSecond", 1, IsUnique = true)]
public int FirstColumn { get; set; }
[Index("IX_FirstAndSecond", 2, IsUnique = true)]
public int SecondColumn { get; set; }
Example 2: how to set unique constraint from EF core
protected override void OnModelCreating(ModelBuilder builder)
{
builder.Entity<User>()
.HasIndex(u => u.Email)
.IsUnique();
}