如何使用SqlCommand和SqlDataReader在C#中返回Json结果

本文关键字：返回 Json 结果 何使用 SqlCommand SqlDataReader | 更新日期: 2023-09-27 18:26:19

我正在尝试在SqlCommand中使用SQL查询，我想查看从SQL Server数据库返回的完整结果集，然后返回Json格式。

这是控制器中的代码：

public ActionResult GetAllSummary()
{
    string connectionString ="Data Source=...;Initial Catalog=...;Integrated Security=True";  
    string query = "SELECT v.date, v.name, v.numbers FROM view as v GROUP BY v.date,v.mane,v.numbers ORDER BY v.date,v.mane,v.numbers";
    using(SqlConnection conn = new SqlConnection(connectionString))
    {
        SqlCommand command = new SqlCommand(query, conn);
        try {
            conn.Open();
            SqlDataReader reader = command.ExecuteReader();
            // In this part below, I want the SqlDataReader  to 
            // read all of the records from database returned, 
            // and I want the result to be returned as Array or 
            // Json type, but I don't know how to write this part.
            while(reader.Read())
            {
                ArrayList result = new ArrayList();
                foreach(int i in reader)
                     // this line below was the code I wrote before. 
                     // But since my query returns multiple 
                     // types (datetime, string, decimal, etc..), 
                     // I don't know what C# command I can use to return
                     // the results in foreach loop. Or say I even don't 
                     // need a for/foreach loop.
                     result.Add(reader.GetValue(i));
                return Json(result, JsonRequestBehavior.AllowGet);
            }
            reader.Close();
        }
        catch(Exception ex)
        {
            var error = ex.Message;
            return View(error);
        }
    }
    return View();
}

有人能帮我做这件事吗？我将不胜感激。

Kevin

如何使用SqlCommand和SqlDataReader在C#中返回Json结果

public class data {
  public DateTime date {get;set;}
  public string name {get;set;}
  public int numbers {get;set;}
}
public ActionResult GetAllSummary()
{
    string connectionString ="Data Source=...;Initial Catalog=...;Integrated Security=True";  
    string query = "SELECT DISTINCT v.date, v.name, v.numbers FROM view as v ORDER BY v.date,v.name,v.numbers";
    using(SqlConnection conn = new SqlConnection(connectionString))
    {
        SqlCommand command = new SqlCommand(query, conn);
        try {
            conn.Open();
            SqlDataReader reader = command.ExecuteReader();
            // In this part below, I want the SqlDataReader  to 
            // read all of the records from database returned, 
            // and I want the result to be returned as Array or 
            // Json type, but I don't know how to write this part.
            while(reader.Read())
            {
                List<data> result = new List<data>();
                var d=new data();
                d.date=reader[0]; // Probably needs fixing
                d.name=reader[1]; // Probably needs fixing
                d.numbers=reader[2]; // Probably needs fixing
                result.Add(data);
            }
            reader.Close();
            return Json(result, JsonRequestBehavior.AllowGet);
        }
        catch(Exception ex)
        {
            var error = ex.Message;
            return View(error);
        }
    }
    return View();
}

或

public class data {
  public DateTime date {get;set;}
  public string name {get;set;}
  public int numbers {get;set;}
}
public ActionResult GetAllSummary()
{
    string connectionString ="Data Source=...;Initial Catalog=...;Integrated Security=True";  
    string query = "SELECT DISTINCT v.date, v.name, v.numbers FROM view as v ORDER BY v.date,v.name,v.numbers";
    using(SqlConnection conn = new SqlConnection(connectionString))
    {
        SqlCommand command = new SqlCommand(query, conn);
        try {
            conn.Open();
            SqlDataReader reader = command.ExecuteReader();
            var dt=new DataTable();
            dt.Load(myDataReader);
            List<DataRow> result=dt.AsEnumerable().ToList();
            reader.Close();
            return Json(result, JsonRequestBehavior.AllowGet);
        }
        catch(Exception ex)
        {
            var error = ex.Message;
            return View(error);
        }
    }
    return View();
}

或者（只是有趣的部分）：

var dt=new DataTable();
dt.Load(myDataReader);
object[] result = new object[dt.Rows.Count + 1];
for (int i = 0; i <= dt.Rows.Count - 1; i++) {
    result[i] = dt.Rows[i].ItemArray;
}

您可以使用以下扩展：

public static string ExecuteToJson(this SqlCommand cmd)
{
    if (cmd.Connection.State == ConnectionState.Closed)
    {
        cmd.Connection.Open();
    }
    using (DataTable dt = new DataTable())
    {
        using (SqlDataAdapter da = new SqlDataAdapter(cmd))
        {
            da.Fill(dt);
            List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>();
            Dictionary<string, object> row;
            foreach (DataRow dr in dt.Rows)
            {
                row = new Dictionary<string, object>();
                foreach (DataColumn col in dt.Columns)
                {
                    row.Add(col.ColumnName, dr[col]);
                }
                rows.Add(row);
            }
            return JsonConvert.SerializeObject(rows);
        }
    }
}

以及用途：

string connectionString = "** connstr **";
string query = "SELECT * FROM `table`";
try
{
    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        using (SqlCommand command = new SqlCommand(query, conn))
        {
            string json = command.ExecuteToJson(); 
        }
    }
}
catch (Exception)
{
}
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