获取列表

Question

鲜明的列名我有一个SQL查询这样

SELECT DISTINCT CustomerName FROM Customers 

它返回不同customerNames的名单，

我如何在C＃

目前我得到这个列表我在DataTable中获取结果，然后在列表中只提取我需要的列。

private List<String> GetDistinctCustomerNames() 
{ 
    var dataTable = new DataTable("ResultDataTable"); 
    using (var sqlCommand = new SqlCommand()) 
    { 
     // set the connection for the commnad 
     sqlCommand.Connection = sqlConnection; 

     // assign the insert query as a text to the sql command 
     sqlCommand.CommandText = "SELECT DISTINCT CustomerName FROM Customers"; 

     using (var sqlDataAdapter = new SqlDataAdapter()) 
     { 
      sqlDataAdapter.SelectCommand = sqlCommand; 
      dataTable.Load(sqlCommand.ExecuteReader()); 
     } 

     if (dataTable.Columns.Contains("CustomerName")) 
     { 
      return (from DataRow dataRow in dataTable.Rows select dataRow["CustomerName"].ToString()).ToList(); 
     } 

    return null; 
} 

但我不觉得这是一个很好的解决方案。

Answer 1

而是有你为该回报我会做一个foreach

ForEach(var element in DataTable.Rows) 
    if(element.CustomerName != NULL) 
     list.add(element.ToString()) 
     //To string is only needed if the db stores it as not an nvarchar or something like that 

return list 

Answer 2

你应该更googling OR https://stackoverflow.com/a/19406319/2089368 ...

Answer 3

后你从方法列表中，您可以应用下面的代码。

// Get distinct elements and convert into a list again. 
List<string> distinct = list.Distinct().ToList();