Question

我使用LinqPad执行一些动态sql，当我调用.Dump（）时它返回IEnumerable。我希望它显示其返回的匿名类型的结果。有关在LinqPad中执行动态sql语句并显示结果的任何帮助都将不胜感激。

以下是我要做的事情的代码片段：

// Any sql string for example.
var query = "SELECT DISTINCT [CustomerId] FROM Customers Where CustomerId = 2";

var dyn = this.ExecuteQuery<dynamic>(query);

LINQPad.Extensions.Dump(dyn);

Answer 1

你在IDataRecord的正确轨道上。要使输出动态化，请使用DynamicObject：

static class Extensions
{
    public static IEnumerable<dynamic> ExecuteSQL (this DataContext dc, string sql)
    {
        var cx = new SqlConnection (dc.Connection.ConnectionString);
        cx.Open();
        return new SqlCommand (sql, cx).ExecuteReader (CommandBehavior.CloseConnection).Cast<IDataRecord>().Select (r => new DynamicDataRecord (r));
    }
}

class DynamicDataRecord : System.Dynamic.DynamicObject
{
    readonly IDataRecord _row;
    public DynamicDataRecord (IDataRecord row) { _row = row; }

    public override bool TryConvert (System.Dynamic.ConvertBinder binder, out object result)
    {
        if (binder.Type == typeof (IDataRecord))
        {
            result = _row;
            return true;
        }
        return base.TryConvert (binder, out result);
    }

    public override bool TryInvokeMember (System.Dynamic.InvokeMemberBinder binder, object [] args, out object result)
    {
        if (binder.Name == "Dump")
        {
            if (args.Length == 0)
                _row.Dump ();
            else if (args.Length == 1 && args [0] is int)
                _row.Dump ((int)args [0]);
            else if (args.Length == 1 && args [0] is string)
                _row.Dump ((string)args [0]);
            else if (args.Length == 2)
                _row.Dump (args [0] as string, args [1] as int?);
            else
                _row.Dump ();
            result = _row;
            return true;
        }
        return base.TryInvokeMember (binder, args, out result);
    }

    public override bool TryGetMember (System.Dynamic.GetMemberBinder binder, out object result)
    {
        result = _row [binder.Name];
        if (result is DBNull) result = null;
        return true;
    }

    public override bool TryGetIndex (System.Dynamic.GetIndexBinder binder, object [] indexes, out object result)
    {
        if (indexes.Length == 1)
        {
            result = _row [int.Parse (indexes [0].ToString ())];
            return true;
        }
        return base.TryGetIndex (binder, indexes, out result);
    }

    public override IEnumerable<string> GetDynamicMemberNames ()
    {
        return Enumerable.Range (0, _row.FieldCount).Select (i => _row.GetName (i));
    }
}

这将允许以下内容：

this.ExecuteSQL ("select * from customer").GroupBy (c => c.Name).Dump();

编辑：从v4.53.02起，此功能现在可在LINQPad中使用。你现在可以去：

ExecuteQueryDynamic ("SELECT DISTINCT * FROM Customer WHERE ID = {0}", 2)

Answer 2

所以我为获得结果所做的就是这样，但我认为必须有更好的方法。

using (SqlConnection connection = new SqlConnection(this.Connection.ConnectionString))
{
  connection.Open();

  SqlCommand command = new SqlCommand(query, connection);
  SqlDataReader reader = command.ExecuteReader();

  reader.Cast<IDataRecord>().AsQueryable().Dump();      
}

Answer 3

除了Joe's answer：

您使用 Linq-to-SQL 连接非常重要，因为ExecuteQueryDynamic
实体框架中的不可用。

以下是如何在LinqPad 5中将不同的数据类型作为参数（基于 Northwind 数据库）处理：

void Main()
{
    // Boolean
    ExecuteQueryDynamic(@"DECLARE @Discontinued bit={0}; 
                        SELECT DISTINCT * FROM Products 
                        WHERE Discontinued = @Discontinued", true).Dump();
    // Int
    ExecuteQueryDynamic(@"DECLARE @OrderId Int={0}; 
                        SELECT DISTINCT OrderId, CustomerId, ShipName FROM Orders 
                        WHERE OrderID = @OrderId", 10248).Dump();
    // String
    ExecuteQueryDynamic(@"DECLARE @CustomerId nvarchar(max)={0}; 
                        SELECT DISTINCT * FROM Customers 
                        WHERE CustomerId = @CustomerId", "VINET").Dump();
}

我建议您对SQL变量使用DECLARE语句。这样，您可以先在T-SQL（或LinqPad SQL模式）中使用指定的固定值进行尝试 - 如果数据类型不匹配，您将收到有意义的错误消息，然后您可以将其插入ExecuteQueryDynamic并插入{{ 1}}对于first，second，third，...参数如下：

{0}, {1}, {2} ...

注意： ExecuteQueryDynamic不支持多个结果集。这意味着，只允许一个SELECT语句，其他的语句将被忽略。

LinqPad动态sql并显示结果

3 个答案: