使用带 ADO.NET 的 DbContext 的良好查询不返回任何结果

Question

我需要 运行 在我的数据库上下文中进行以下查询。

SELECT u.[Email],
u.[EmailConfirmed],
u.[PhoneNumber],
STRING_AGG(r.[Name], ', ') AS Roles
FROM [AspNetUsers] u
LEFT OUTER JOIN [AspNetUserRoles] ur ON ur.UserId = u.Id
LEFT OUTER JOIN [AspNetRoles] r ON r.Id = ur.RoleId
GROUP BY u.[Email], u.[EmailConfirmed], u.[PhoneNumber]

当我在查询window中运行这个时，我得到了四个结果。所以我想出了下面的代码。

string UserQuery = @"SELECT u.[Email],
u.[EmailConfirmed],
u.[PhoneNumber],
STRING_AGG(r.[Name], ', ') AS Roles
FROM [AspNetUsers] u
LEFT OUTER JOIN [AspNetUserRoles] ur ON ur.UserId = u.Id
LEFT OUTER JOIN [AspNetRoles] r ON r.Id = ur.RoleId
GROUP BY u.[Email], u.[EmailConfirmed], u.[PhoneNumber]";

var conn = DbContext.Database.GetDbConnection();
using var cmd = conn.CreateCommand();
cmd.CommandText = UserQuery;
DbContext.Database.OpenConnection();
using var reader = cmd.ExecuteReader();
while (reader.NextResult())
{
    Users.Add(new UserViewModel
    {
        Email = (string)reader["Email"],
        EmailConfirmed = (bool)reader["EmailConfirmed"],
        Phone = (string)reader["PhoneNumber"],
        Role = (string)reader["Roles"]
    });
}

这段代码运行s没有错误，但是第一次调用reader.NextResult() returns false!

谁能看到我遗漏了什么？

Answer 1

应该是 reader.Read() 因为 reader.NextResult() 会返回下一个结果 set

参见：

Difference between SqlDataReader.Read and SqlDataReader.NextResult