What is the method to retain previously entered information while adding new data through seed in .net core?

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One approach to retain previously entered information while adding new data through seed in .NET Core is to use a database migration framework such as Entity Framework Core. This framework allows for creating and applying database migrations that allow for modifying database structure and data migration.

To retain previously entered information, a migration can be created that adds the new data while preserving existing data. This can be done using the Up method of the migration, which is executed when the migration is applied. The Up method can include SQL statements or code to add new data to the database.

For example, suppose a Customers table already exists in the database, and we want to add new customers through a seed file while preserving the existing customers. We can create a migration named AddNewCustomers and add the following code to the Up method:

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.InsertData(
        table: "Customers",
        columns: new[] { "FirstName", "LastName", "Email" },
        values: new object[] { "John", "Doe", "johndoe@example.com" });

    migrationBuilder.InsertData(
        table: "Customers",
        columns: new[] { "FirstName", "LastName", "Email" },
        values: new object[] { "Jane", "Doe", "janedoe@example.com" });
}

This code uses the InsertData method to add two new customers to the Customers table. When the migration is applied, these customers will be added to the database while preserving any previously entered customer data.

To apply the migration, we can use the Update-Database command in the Package Manager Console:

PM> Update-Database

This will apply any pending migrations, including our AddNewCustomers migration, to the database.

Overall, using a database migration framework like Entity Framework Core can help maintain database schema and data consistency while allowing for adding new data through seed files.