Table

[Table("tblBlog", Schema="journal")]
public class Blog
{
     ...
}

This example has a different table name from the class name and is in a schema other than dbo. This is useful when connecting to existing databases and it is not appropriate to carry forwards the name into the application.

Primary Key Field

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.None)]
public int BlogId { get; set; }

DatabaseGeneratedOption can have three options None, Identity and Computed.

Composite Keys

public class UserRole
{
    [Key]
    [Column(Order = 1)]
    public int UserId { get; set; }

    [Key]
    [Column(Order = 2)]
    public int RoleId { get; set; }
}

Null Fields

A column is nullable if a property is nullable.

[Required]
public string Name { get; set; }

[Required]
public Author Author { get; set; }

Field

[Column("BlogName", TypeName="VARCHAR")]
[MaxLength(450)]
[Required]
public string Name { get; set; }

Note that the field name is different from the property name.

Field Index

[Index]
public int Rating { get; set; }

[Index("PostRatingIndex")]
public int Rating { get; set; }

An index in multiple columns

[Index("IX_AuthorStudentCount", 1)]
public int AuthorId{ get; set; }

[Index("IX_AuthorStudentCount", 2)]
public int StudentCount{ get; set; }

Unique Index

[Index(IsUnique = true)]
public string Name { get; set; }

Field Database Generated

[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public DateTime DateCreated { get; set; }

Foreign Keys

Method 1

Explicity link the foreign key id with the parent entity, with an annotation.

public class Course
{
    [ForeignKey("Author")]
    public string AuthorId { get; set; }

    public Author Author { get; set; }
}

Method 2

Explicity link the parent entity with the foreign key id, with an annotation.

public class Course
{
    public string AuthorId { get; set; }

    [ForeignKey("AuthorId")]
    public Author Author { get; set; }
}

Entity Framework