带有EF Core的类似Dapper的多查询

问题描述

使用dapper，一次运行多个查询非常容易:

With dapper it is pretty easy to run mulitple queries in one run:

string sql = "SELECT * FROM Invoice WHERE InvoiceID = @InvoiceID; SELECT * FROM InvoiceItem WHERE InvoiceID = @InvoiceID;";

using (var connection = My.ConnectionFactory())
{
    connection.Open();

    using (var multi = connection.QueryMultiple(sql, new {InvoiceID = 1}))
    {
        var invoice = multi.Read<Invoice>().First();
        var invoiceItems = multi.Read<InvoiceItem>().ToList();
    }
}

如何使用EFCore归档?

How to archieve this with EFCore?

我找到了类似的解决方案

I found solutions like

var query = from _ in db.Invoices
            select new {
                Invoice = db.Invoices.Single(x=>x.InvoiceId == 1),
                InvoiceItems = db.InvoiceItems.Where(x=>x.InvoiceId == 1),
            }

但是这不起作用.我可以在配置文件中看到这在两个连接中运行两个查询.我什至可以看到连接没有被重用(为什么?).

but this does not work.I can see in the profiling this runs two queries in two connections. I can even see that the connection is not reused (why?).

如何使用EFCore运行多个查询，这是EFCore巨大的性能不足吗?谢谢.

How to run multiple queries with EFCore is this a big performance-lack of EFCore?Thanks.

推荐答案

问题是:MultiActiveResults为假.

The problem was: MultiActiveResults was false.

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