如何将SqlDataReader转换为LINQ方式？

Question

我不知道如何将SqlDataReader转换为LINQ方式？

这是我的SqlDataReader代码。

string strConn = "server=xxx.com;database=mydb;User ID=test;Password=test;Trusted_Connection=true;"; 
SqlConnection myConn = new SqlConnection(strConn); 
myConn.Open(); 

string strSQL = "select period from timetable_view where identity_num = '" + Identity_NUM + "' week = '3'"; 
SqlCommand myCommand = new SqlCommand(strSQL, myConn); 
SqlDataReader myDataReader = myCommand.ExecuteReader(); 

int Count = Add_CourseConfirmedQuery.Count(); 

Random rnum = new Random(); 
string[] arr = new string[Count]; 
for (int i = 0; i < Count; i++) 
{ 
    myDataReader.Read(); 
    arr[i] = myDataReader["period"].ToString(); 
} 
ViewBag.test = arr[0]; 
ViewBag.test2 = arr[1]; 

myCommand.Cancel(); 
myDataReader.Close(); 
myConn.Close(); 
myConn.Dispose(); 

string[] input2 = new string[Count]; 

for (int i = 0; i < Count; i++) 
{ 
    input2[i] = arr[i]; 
} 

此代码正常工作。

我试过在LINQ中编码，但它不起作用。

这是我尝试过的LINQ代码，但我不知道如何提取a.identity_num的所有记录，并将它们放入像上面的代码（SqlDataReader）那样的数组中。

var test = from a in timetable_view 
      where a.identity_num = Identity_NUM && a.week = "3" 
      select a new{a.identity_num}; 

ViewBag.test = test.FirstOrDefault(); 

[更新问题]

这就是我现在想。

我无法从我的表中提取正确的记录。

但页面显示：System.String []

var Query = from m in db.members 
      join d in db.departments on m.department equals d.department_id 
      join s in db.select_list on m.member_id equals s.member_id 
      join c in db.courses on s.kkk_id equals c.kkk_id 
      join t in db.teachers on c.teacher equals t.teacher_id 
      where m.identity_num == Identity_NUM && c.week == "3" 
      select c.period; 
      var PA = Query.ToArray(); 
      int Count = Query.Count(); 


string[] arr = new string[Count]; 
      for (int i = 0; i < Count; i++) 
      { 
       arr[i] = PA.ToString(); 
      } 
      ViewBag.test = arr[0]; 
      ViewBag.test2 = arr[1]; 
............. 
............ 
........... 

string[] input2 = new string[Count]; 
     for (int i = 0; i < Count; i++) 
     { 
      input2[i] = arr[i]; 
     } 
............. 
............ 
........... 

Answer 1

更新以匹配更改的问题：

不要选择一个新的匿名对象，只需选择值：

var arr= (from a in timetable_view 
      where a.identity_num = Identity_NUM && a.week = "3" 
      select a.period).ToArray(); 

全面更新变化应

var Query = from m in db.members 
      join d in db.departments on m.department equals d.department_id 
      join s in db.select_list on m.member_id equals s.member_id 
      join c in db.courses on s.kkk_id equals c.kkk_id 
      join t in db.teachers on c.teacher equals t.teacher_id 
      where m.identity_num == Identity_NUM && c.week == "3" 
      select c.period; 


var arr = Query.ToArray();  

ViewBag.test = arr[0]; 
ViewBag.test2 = arr[1]; 

从注释：由具有的ToString（）中的代码生成

• 该错误消息表示我们，周期是无论如何一个字符串，所以该呼叫可以被去除。

• 为了得到计数，int Count = arr.Length

• for循环已被删除，因为它是多余的，使用ToArray的（）函数达到相同的结果。

Answer 2

你需要的LINQ查询转换为数组。贝娄代码应该这样做：

var test = (from a in school_timetable_view 
      where a.identity_num == Identity_NUM && a.week == "3" 
      select a new{a.identity_num}).ToArray(); 

Answer 3

如果您需要linkq转换为指定者：

var TEST = (from a in timetable_view 
      where a.identity_num = Identity_NUM && a.week = "3" 
      select a new{a.identity_num}).ToArray(); 

var Query = from m in db.members 
      join d in db.departments on m.department equals d.department_id 
      join s in db.select_list on m.member_id equals s.member_id 
      join c in db.courses on s.kkk_id equals c.kkk_id 
      join t in db.teachers on c.teacher equals t.teacher_id 
      where m.identity_num == Identity_NUM && c.week == "3" 
      select c.period.ToString(); 


var arr = Query.ToArray();  

ViewBag.test = arr[0]; 
ViewBag.test2 = arr[1];