![]() ![]() The composite key does not create an identity column for the integer property. Note: In EF 6, the Key attribute creates a PK with an identity column when applied to a single integer type property. The above code creates composite primary key columns StudentKey and AdmissionNum in the Students table as shown below. ![]() You have to use the Fluent API HasKey() function in EF Core. A primary key that is made by the combination of more than one attribute is known. This MS doc article - Alternate Keys (Unique Constraints) - will explain how to use and which. In EF 6, the Key attribute along with the Column attribute can be applied to multiple properties of an entity class which will create composite primary key columns in the database.ĮF Core does not support creating a composite key using the Key attribute. Sometimes more than one attributes are needed to uniquely identify an entity. There are no data annotations to realize a unique constraint. The ForeignKey and InverseProperty attributes. The Key attribute can be applied to a property of any primitive data type except unsigned integers. The Data Annotations approach contains only two attributes related to relationships. You can configure foreign key properties using the ForeignKey annotation to clarify your intention to Code First. This will override the default conventions and create a primary key column StudentKey in the Students table in the database as shown below. Fixing foreign key with Data Annotations. Using Īs you can see in the above example, the Key attribute is applied to the StudentKey property of the Student entity class. The Entity Framework core automatically creates an Alternate key if you define a relationship on any property. If table has composite primary key then it is throwing error 'Entity type has composite primary key defined with data annotations. There is no direct alternative to the HasAlternateKey method in data annotations or in default convention. The Key attribute overrides this default convention. The alternative key can be composed of multiple columns. The default convention creates a primary key column for a property whose name is Id or Id. The Key attribute can be applied to a property in an entity class to make it a key property and the corresponding column to a PrimaryKey column in the database. ![]() Please see if any of you experts can help.Next Data Annotations - Key Attribute in EF 6 & EF Core But the second model is not allowing me use of another Column. The performance issue occurs on 200k data table whenever I search an entity without primary key (i.e a string of GUID). In this article, you'll learn how to map a composite primary key in a Spring Boot project using Spring Data JPA's both IdClass and EmbeddedId annotations. While the Account can be identified by Source System ( SrcSys), Customer ID ( CustId) plus Account Id ( AccId). Shortly, I want to create composite keys on my table remaining with the primary key in order to improve sql server search performance. Simply put, a composite primary key, also known as a composite key, is a key that contains two or more columns to form a primary key for the table. The Customer can be identified by the Composite Key Source System ( SrcSys) & Customer ID ( CustId). Data annotations and the fluent API can be used together, but Code First gives precedence to Fluent API > data. Entity Framework Core supports composite keys - primary key values generated from two or more fields in the database. I have a two following 2 models in an MVC project: using Fluent API is an advanced way of specifying model configuration that covers everything that data annotations can do in addition to some more advanced configuration not possible with data annotations. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |