# Entity Framework Glossary | EF6 Tutorial and Documentation

Architecture

Term	Definition
Entity Client	Entity client provides the ability to work against entities in the form of rows and columns using SQL queries.
Entity Layer	Entity Layer defines the entities and relationships.
Mapping layer	Mapping layer maps the entities and relationships defined at conceptual layer with actual relationships and tables defined at logical layer.
Object Service	Object Services provides the functionality needed to work with objects that are based on your entities.
Storage Layer	Storage Layer contains the entire database schema in XML format.

Asynchronous Programming

Term	Definition
Asynchronous Query	Entity Framework supports asynchronous operations for querying and saving of data.

Container

Term	Definition
Entity Container	Specifies entity sets and association sets that will be implemented in a specified namespace.
Entity Set	A logical container for entities of a given type and its subtypes. Entity sets are mapped to tables in a database.

Convention

Term	Definition
Convention (Code First)	A rule that Entity Framework uses to infer the shape of your model from your classes.

Data Annotations

Term	Definition
Column	Specifies the database column that a property is mapped to.
ConcurrencyCheck	Specifies that a property participates in optimistic concurrency checks.
Data Annotations	DataAnnotations is used to configure the classes which will highlight the most commonly needed configurations.
ForeignKey	Denotes a property used as a foreign key in a relationship
Index	Specifies that the database column to which the property is mapped has an index.
InverseProperty	Specifies the inverse of a navigation property that represents the other end of the same relationship.
Key	Denotes one or more properties that uniquely identify an entity.
MaxLength	Specifies the maximum length of array or string data allowed in a property.
MinLength	Specifies the minimum length of array or string data allowed in a property.
NotMapped	Denotes that a property or class should be excluded from database mapping.
Required	Specifies that a data field value is required.
StringLength	Specifies the minimum and maximum length of characters that are allowed in a data field.
Table	Specifies the database table that a class is mapped to.
TimeStamp	Specifies the database column with timestamp datatype, and it can be applied to only one byte array property of a domain class.

Data Concurrency

Term	Definition
Concurrency Conflicts	A concurrency conflict occurs when one user displays an entity's data in order to edit it, and then another user updates the same entity's data before the first user's change is written to the database.
Handling Optimistic Concurrency	In the database table, include a tracking column that can be used to determine when a row has been changed.
Optimistic Concurrency	EF saves the entity to the database, assuming that the same data has not changed since the entity was loaded.
Pessimistic Concurrency (Locking)	Locking a row for update access, and no other users are allowed to` lock the row either for read-only or update access

Data Model

Term	Definition
Entities	Blueprints for Business Classes, e.g. Invoice, InvoiceItem, etc.
Entity Data Model (EDM)	EDM is an extended version of the ERM which specifies client-side data model, and it is the core of the Entity Framework
Entity Relationship Model (ERM)	ERM defines a schema of entities and their relationships with one another.
Inheritance	Inheritance used with entities serves the same purpose as inheritance used with classes
Storage Model	A definition for the logical model of data in a supported data source, such as a relational database.

Database

Term	Definition
Indexs	An index is an on-disk data structure that is based on tables and views. Indexes make the retrieval of data faster and efficient, in most cases.
Stored Procedures	Entity Framework allows you to use stored procedures to perform predefined logic on database tables,
Table-Valued Function (TVF)	TVF is very similar to stored procedures but with one key difference, i.e., the results from a TVF can be used in a LINQ query while the results of a stored procedure cannot.
Views	A view is an object that contains data obtained by a predefined query.

Database Operations

Term	Definition
Create Operation	Adding a new object is as simple as constructing a new instance of your object and add it using the Add method on DbSet.
Delete Operation	To delete an entity using Entity Framework, you use the Remove method on DbSet.
Read Operation	Reading the existing data from the database
Update Operation	Changing existing objects is as simple as updating the value assigned to the property(s) and calling SaveChanges.

Database Transaction

Term	Definition
BeginTransaction	It allows several operations to be combined within the same transaction and hence either all are committed, or all are rolled back as one.
Transaction	Combining several database operations (insert, update, delete etc.) into one transaction
UseTransaction	It allows the DbContext to use a transaction, which was started outside of the Entity Framework.

Dev Approaches

Term	Definition
Code First	In Code First, POCO classes are created first, and the database is generated from these POCO classes.
Database First	In this approach data model, context and entity classes are created from an existing database.
Model First	In this approach, Entities, relationships, and inheritance hierarchies are created in EF designer first, and then a database is generated from that model.

Entities & DbContext

Term	Definition
Change Tracking	Change Tracking tracks the changes made to entities and their relations
DbContext	The primary class that is responsible for interacting with data as objects is called DbContext class.
Disconnected Entities	Entities that are not being tracked by a context are known as disconnected entities.
POCO Entities	POCO stands for "plain-old" CLR objects which can be used as an existing domain objects with the data model.
Seed Database	A method that should be overridden to add data to the context for seeding.
Self-tracking Entity	An entity built from a code generation template that helps with N-Tier development.

Enum Support

Term	Definition
Enum Support	Entity Framework allows you to define a property on a domain class that is an enum type and map it to a database column of an integer type.

Fluent API

Term	Definition
Fluent API	An API that can be used to configure a Code First model. Fluent API covers everything that data annotations can do in addition to some more advanced configuration not possible with data annotations.

Fluent API Entity Mapping

Term	Definition
Default Schema	Configures the default database schema name. This default database schema name is used for database objects that do not have an explicitly configured schema name.
Entity Mapping	Entity mapping is just some simple mappings that will impact Entity Framework's understanding of how the classes are mapped to the databases.
Entity Splitting	Entity Splitting lets you combine data coming from multiple tables into a single class, and it can only be used with tables that have a one-to-one relationship between them.
Map Entity to Table	Configures the table name that this entity type is mapped to.

Fluent API Properties Mapping

Term	Definition
HasColumnName	Configures the name of the database column used to store the property.
HasColumnOrder	Configures the order of the database column used to store the property.This method is also used to specify key ordering when an entity type has a composite key.
HasColumnType	Configures the data type of the database column used to store the property.
HasKey	Configures the primary key property(s) for this entity type.
HasMaxLength	Configures the property to have the specified maximum length.
IsConcurrencyToken	Configures the property to be used as an optimistic concurrency token.
IsRequired	Configures the property to be required. The database column used to store this property will be non-nullable.
IsUnicode	Configures the property to support Unicode string content.
Properties Mapping	The Property method is used to configure attributes for each property belonging to an entity or complex type.

Lifecycle

Term	Definition
Context Lifetime	The lifetime of a context begins when the instance is created and ends when it is either disposed or garbage-collected.
Entity Lifecycle	The Entity Lifecycle describes the process in which an Entity is created, added, modified, deleted, etc.

Loading Related Entities

Term	Definition
Eager Loading	Eager loading is the process where a query for one type of entity also loads related entities as part of the query.
Explicit Loading	When you disable the lazy loading, it is still possible to lazily load related entities, but it must be done with an explicit call.
Lazy Loading	Lazy loading means delaying the loading of related data, until you specifically request for it.

Logging SQL

Term	Definition
Logging SQL	It captures an equivalent SQL query generated by Entity Framework internally and provides it as output.

Mapping

Term	Definition
Object-Relational Mapping	A technique for transforming data from a relational database into data types that can be used in object-oriented software applications.
Table-per-concrete type (TPC)	A method of mapping the inheritance where each non-abstract type in the hierarchy is mapped to separate table in the database.
Table-per-hierarchy (TPH)	A method of mapping the inheritance where all types in the hierarchy are mapped to the same table in the database. A discriminator column(s) is used to identify what type each row is associated with.
Table-per-type (TPT)	A method of mapping the inheritance where the common properties of all types in the hierarchy are mapped to the same table in the database, but properties unique to each type are mapped to a separate table.

Migration

Term	Definition
Automated Migration	Automatic Migrations allows you to use Code First Migrations just by executing a command in Package Manager Console
Code Based Migration	Configures the Entity Framework to automatically drop and re-create the database each time you change the data model.
Migration	Migration is a process in which any change in a database will also need to change the data model and vice versa.

Object

Term	Definition
Object Layer	The entity types and object context definitions that are used by the Entity Framework.
Object Query	A query executed within an object context against a conceptual model that returns data as objects.
Proxy Object	An object that derives from a POCO class and is generated by the Entity Framework to support change tracking and lazy loading.

Querying Data

Term	Definition
Command Tree	A common, programmatic representation of all Entity Framework queries that are composed of one or more expressions.
LINQ to Entities	LINQ to Entities enables developers to write queries against the Entity Framework conceptual model in a declarative language.
Projection Queries	Projection queries improve the efficiency of your application, by only retrieving specific fields from your database.

Relationships

Term	Definition
Foreign key association	An association between entities where a property that represents the foreign key is included in the class of the dependent entity
Identifying relationship	A relationship where the primary key of the principal entity is part of the primary key of the dependent entity. In this kind of relationship, the dependent entity cannot exist without the principal entity.
Independent association	An association between entities where there is no property representing the foreign key in the class of the dependent entity.
Many-to-Many Relationship	A row in table A can have many matching rows in table B, and vice versa.
Multiplicity	The number of entities that can exist on each side of a relationship, as defined by an association also known as cardinality.
Navigation Property	A property of an entity that references another entity, e.g., Invoice contains an InvoiceItems navigation property.
One-to-Many Relationship	A row in table A can have many matching rows in table B, but a row in table B can have only one matching row in table A, e.g., an Invoice can have multiple InvoiceItems
One-to-One Relationship	A row in table A can have no more than one matching row in table B, and vice versa. E.g., each Invoice can have a unique InvoiceDetail
Relationships	The relationship is a situation that exists between relational database tables through foreign keys.

Spatial Data

Term	Definition
Spatial Data	Entity Framework supports spatial data types DbGeography and DbGeometry which allow queries to analyze spatial data. e.g., a query can filter based on the distance between two geographic locations.

SQL

Term	Definition
Entity SQL	A storage-independent dialect of SQL that works directly with conceptual entity schemas and that supports conceptual model concepts such as inheritance and relationships.
Native SQL	You can run queries using raw SQL directly against the database using DbContext.
SQL Commands	ExecuteSqlCommnad method is used in sending non-query commands to the database, such as the Insert, Update or Delete command.

Type

Term	Definition
Complex Type	The specification for a data type that represents a non-scalar property of an entity type that does not have a key property.
entity type	A .NET Framework class that represents an entity as it is defined in the conceptual model.
Multiple Entity Sets Per Type	The ability for an entity type to be defined in more than one entity set.

Validation

Term	Definition
ValidateEntity	DbContext has an Overridable method called ValidateEntity and validation logic can be put in here directly.
Validation	Entity Framework provides a great variety of validation features can be implemented to both client-side and server-side validation.

General

Term	Definition
Referential Constraint	A constraint that is defined in a conceptual model that indicates that an entity has a dependent relationship to another entity.
Simple Type	A primitive type that is used for defining properties in the conceptual model.