将 linq 查询另存为数据表

Question

在c#MVC中，我需要在数据表中得到如下的“结果”（var）。

var allCompanies = objentity.ExecuteFunction<SearchAvailEmployees_Result>("SearchAvailEmployees", lstParam.ToArray())
                            .ToList();

var result = from c in allCompanies select new[] { 
                            c.LastName, 
                            c.FirstName, 
                            c.Phone, 
                            c.City, 
                            c.PositionApplied, 
                            c.Status, 
                            Convert.ToString(c.CallDate.Value.ToShortDateString()), 
                            Convert.ToString(c.CellOrPager), 
                            c.Gender 
                        };

我尝试了以下代码，但它不起作用。它给出的错误为

“无法将类型 'System.Collections.Generic.IEnumerable' 隐式转换为 'System.Collections.Generic.IEnumerable'。存在显式转换（您是否缺少强制转换？）”

IEnumerable<DataRow> query = from c in allCompanies select new[] { 
                                            c.LastName, 
                                            c.FirstName, 
                                            c.Phone, 
                                            c.City, 
                                            c.PositionApplied, 
                                            c.Status, 
                                            Convert.ToString(c.CallDate.Value.ToShortDateString()), 
                                            Convert.ToString(c.CellOrPager), 
                                            c.Gender 
                                        };

DataTable boundTable = query.CopyToDataTable<DataRow>();

将linq查询结果保存在数据表中的任何替代解决方案？

Answer 1

这就是我的做法：

首先我声明一个新的DataTable 并在此添加列：

DataTable dt = new DataTable();
dt.Columns.Add("FirstName");
dt.Columns.Add("LastName");
DataRow row = null;

现在我执行所需的查询：

var query = from c in allCompanies select { c.LastName, c.FirstName};

现在我只需遍历查询并填写DataTable：

foreach (var rowObj in query)
{
    row = dt.NewRow();
    dt.Rows.Add(rowObj.FirstName, rowObj.LastName);
}
return dt;

在我的查询中，我仍在使用“加入”语句。

Answer 2

首先，使用正确的架构创建DataTable：

var dataTable = new DataTable();
            dataTable.Columns.Add("LastName", typeof (string));
            dataTable.Columns.Add("FirstName", typeof(string));
            // Add more columns

二、选择值对象数组：

var result = allCompanies.Select(c => new object[] {
                    c.LastName, 
                    c.FirstName, 
                    c.Phone, 
                    c.City, 
                    c.PositionApplied, 
                    c.Status, 
                    Convert.ToString(c.CallDate.Value.ToShortDateString()), 
                    Convert.ToString(c.CellOrPager), 
                    c.Gender 
                }).ToList();

第三，循环从DataTable创建新Row并将值赋给新Row：

result.Foreach(array => {
     var row = dataTable.NewRow();
     row.ItemArray = array;
     dataTable.Rows.Add(row);
    });

Answer 3

你应该在new之后删除[]，它就像

var result = from c in allCompanies 
             select new { c.LastName, c.FirstName, c.Phone, c.City, 
             c.PositionApplied, c.Status, 
             CallDate = Convert.ToString(c.CallDate.Value.ToShortDateString()), 
             CellOrPager = Convert.ToString(c.CellOrPager), c.Gender };

在此处创建数据表

var dataTable = new DataTable();
dataTable.Columns.AddRange( new DataColumn[]{ 
    new DataColumn("LastName" , typeof(string)),
    new DataColumn("FirstName" , typeof(string)),
    new DataColumn("Phone" , typeof(string)),
    new DataColumn("City" , typeof(string)),
    new DataColumn("PositionApplied" , typeof(string)),
    new DataColumn("Status" , typeof(string)),
    new DataColumn("CallDate" , typeof(string)),
    new DataColumn("CellOrPager" , typeof(string)),
    new DataColumn("Gender" , typeof(string))
});

使用此结果填充 DataTable

result.ToList().ForEach(x=>{
   var row = dataTable.NewRow();

   row.["LastName"] = x.LastName;
   row.["FirstName"] = x.FirstName;
   row.["Phone"] = x.Phone;
   row.["City"] = x.City;
   row.["PositionApplied"] = x.PositionApplied;
   row.["Status"] = x.Status;
   row.["CallDate"] = x.CallDate;
   row.["CellOrPager"] = x.CellOrPager;
   row.["Gender"] = x.Gender;

   dataTable.Rows.Add(row);
});