什么是 sql 匿名对象，我将如何使用它？ 它出现在我正在关注的在线教程中

Question

What is a sql anonymous object and how would i use it? It came up in an online tutorial i'm following.

Sample code:

Sql = "select Id from dbo.contacts where FirstName = @FirstName and LastName = @LastName;";
int contactId = DB.LoadData<IdLookupModel, dynamic>(Sql, new
    {
        contact.BasicInfo.FirstName,
        contact.BasicInfo.LastName
    },
    _ConnectionString).First().id;

Answer 1

The anonymous object is not part of sql but of your dotnet code. See https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/anonymous-types for more details.

In general you can say that you may create any object without a corresponding class. In your example this is the anonymous object:

new {
    contact.BasicInfo.FirstName,
    contact.BasicInfo.LastName
}

It is passed as the parameters to you sql queries and then mapped to @FirstName and @LastName . The names are taken from the property names. You can also set your own names:

new {
    GivenName = contact.BasicInfo.FirstName,
    FamilyName = contact.BasicInfo.LastName
}

You can than access the parameters via @GivenName and @FamilyName .