I have the following code and basically I want it go step by step using the If statements. When I run this however I get this asp error: "This command requires an asynchronous connection. Set "Asynchronous Processing=true" in the connection string."
On this bit of code:
"addToTable.BeginExecuteReader();"
However I do not want it to by async I want it to run the subsequent queries only if the previous conditions are met.
Full code is below:
string dataset="";
if (System.Web.HttpContext.Current.Session["user"] != null)
{
if (name != null && carId != null)
{
using (SqlConnection con = new SqlConnection(st))
{
string getCar = "SELECT * FROM [Car] WHERE CarId = #carId";
SqlCommand cmd = new SqlCommand(getCarData, con);
cmd.Parameters.AddWithValue("#carId", carId);
using (cmd)
{
con.Open();
SqlDataReader data = cmd.ExecuteReader();
if (data.HasRows)
{
while (data.Read())
{
if (data["available"].ToString() == "0")
{
data.Close();
SqlCommand getParts = new SqlCommand("SELECT * FROM [CarCustomer] WHERE UserId = #UserId AND car=#carId", con);
getParts.Parameters.AddWithValue("#userId", System.Web.HttpContext.Current.Session["userId"]);
getParts.Parameters.AddWithValue("#carId", carId);
SqlDataReader grabRows = getParts.ExecuteReader();
if (grabRows.HasRows)
{
grabRows.Close();
SqlCommand updateTable = new SqlCommand("UPDATE [Table1] SET salesAmount=5 WHERE UserId=1", con);
updateTable.BeginExecuteReader();
}
else
{
grabRows.Close();
SqlCommand addToTable = new SqlCommand("INSERT INTO [Table1] (salesAmount) Values("1")", con);
addToTable.BeginExecuteReader();
}
dataset="good"
}
}
}
}
}
}
}
return dataset;
Instead of BeginExecuteReader command use SqlCommand.ExecuteNonQuery , because ExecuteNonQuery is used to perform query like insert,update and delete where as for Gettting data Read method is used.
one more thing BeginExecuteReadermethod is used to perfrom asncy read operation so if you dont want that than just use ExecuteReadermethod to get data.
Read SqlCommand.ExecuteNonQuery -
You can use the ExecuteNonQuery to perform catalog operations (for example, querying the structure of a database or creating database objects such as tables), or to change the data in a database without using a DataSet by executing UPDATE, INSERT, or DELETE statements.
Related
I'm trying to run stored procedure in EF7 beta8 to return me a specific data. I'm trying to do it via FromSQL command, but not sure if this is right command.
strSQL = wt.DataSource.StoredProc;
foreach (var p in prms)
{
strSQL = strSQL + " #" + p.Name + " = '" + p.Value + "',";
}
strSQL = strSQL.Remove(strSQL.Length - 1); //removes last comma
var test = _dbContext.Widgets.FromSql("EXEC " + strSQL).ToList();
var test2 = _dbContext.Widgets.FromSql("SELECT * FROM Widgets").ToList();
Where test 2 works and returns data correctly, test1 is returning error:
The required column 'Id' was not present in the results of a 'FromSql' operation.
I'm assuming that the data I'm returning is not part of the model. If that's the case, how can I execute stored procedure and return the raw data to List or to DataTable?
EDIT:
I'm trying with SQLCommand:
var connection = (SqlConnection)_dbContext.Database.GetDbConnection();
var command = connection.CreateCommand();
command.CommandType = CommandType.StoredProcedure;
command.CommandText = strSQL;
foreach(var p in prms)
{
command.Parameters.Add("#" + p.Name, p.Value);
}
connection.Open();
var test = command.ExecuteNonQuery();
connection.Close();
Bus still no luck:
No mapping exists from object type Newtonsoft.Json.Linq.JValue to a known managed provider native type.
Is there any other way to execute stored procedure without mapping the entity?
You should be able to use normal SqlCommand and ExecuteReader method to get data from a stored procedure.
Quick sample.
This code executes a stored procedure called GetWidgets which expects 2 parameters, #name and #categoryId and returns a result set which has 2 columns, Id and Name. We are reading the value from the DataReader and creating an object of WidgetDto and appending to a list of WidgetDto.
Your WidgetDto is a simple POCO
public class WidgetDto
{
public int Id {set;get;}
public string Name {set;get;}
}
And the code to execute stored proc is
private List<WidgetDto> GetWidgets(d)
{
var catId= 1;
var name ="test"
//The above values are hard coded for demo. you may replace it
// with whatever your stored proc is expecting.
var list = new List<WidgetDto>();
const string sqlQry = "exec GetWidgets #name,#categoryId";
using (var db = new StudentsEntities())
{
using (var con = (SqlConnection) db.Database.Connection)
{
using (var cmd = new SqlCommand(sqlQry, con))
{
cmd.Parameters.AddWithValue("#name", name);
cmd.Parameters.AddWithValue("#categoryId", catId);
con.Open();
using (var reader = cmd.ExecuteReader())
{
while (reader.Read())
{
var s = new GoodVm();
s.Id = reader.GetInt32(reader.GetOrdinal("Id"));
s.Name = reader.GetString(reader.GetOrdinal("Name"));
list.Add(s);
}
}
}
}
}
return list;
}
In this example, I am using db.DataBase.Connection (Available in ED 6.13 version) property of my DbContext to build the connection. You can build your connection from the legacy way also by using the connection string.
I have created one sp that tuncate table.Table name is dynamic.Here I used dynamic sql.Sp is working fine.I want to execute that sp from C#.net(from cs file).
I know executenonquery returns no of row affected.executenonquery is used for insert,update and delete command.Exectesclare is used for select which has only one cell.EceuteReader is used for selecting multiple record.What shall i use that tell my tuncate table clause executed properly or not?
You can use ExecuteNonQuery to truncate the table.
try
{
string connectionString = ConfigurationManager.ConnectionStrings["MyConnection"].ConnectionString;
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open();
string commandText = "TRUNCATE TABLE myTable";
using (SqlCommand command = new SqlCommand(commandText, connection))
{
command.ExecuteNonQuery();
lblStatus.Text = "Table Deleted Successfully.";
}
}
}
catch(Exception ex)
{
lblStatus.Text = "Table can not be deleted, Error " + ex.Message;
}
I suppose the best way is to use ExecuteNonQuery.
1. It returs the number of rows affected by the statement.
2. And if something doesn't work properly, you will get a nice SqlException which won't go by unnoticed.
try
{
procedure.ExecuteNonQuery();
nextStep.ExecuteWhatever();
}
catch(SqlException e)
{
Console.WriteLine("Oh noes!");
}
I wrote this code in my login page. My code doesn't any error but update query doesn't apply on my database.
Fist query works and I redirect to index.aspx but update query (second query) doesn't apply!!!!
protected void btnLogin_Click(object sender, EventArgs e)
{
Database db1 = new Database();
string query = "select * from Admins where UserName=#username and cast(Password as varbinary)=cast(#password as varbinary)";
SqlCommand smd = new SqlCommand(query, db1.sc);
smd.Parameters.AddWithValue("#username", txtUsername.Text);
smd.Parameters.AddWithValue("#password", General.CreatePasswordHash(txtPassword.Text));
SqlDataReader sdr = smd.ExecuteReader();
smd.Parameters.Clear();
if (sdr.Read())
{
Session.Add("username", sdr[0].ToString());
string nowEnter = sdr[5].ToString();
query = "update Admins set LastEnter=#lastEnter, NowEnter=#nowEnter where UserName=#username";
string now = General.getPersianDateNow() + " ساعت " + General.getPersianTimeNow();
smd.CommandText = query;
smd.Parameters.AddWithValue("#lastEnter", nowEnter);
smd.Parameters.AddWithValue("#nowEnter", now);
smd.Parameters.AddWithValue("#username", sdr[1].ToString());
sdr.Close();
smd.ExecuteNonQuery();
Response.Redirect("~/admin/Index.aspx", false);
}
else
{
lblError.Visible = true;
}
}
In my opinion the problem is with index of sdr. First one you invoke
Session.Add("username", sdr[0].ToString());
Two lines below you use
smd.Parameters.AddWithValue("#username", sdr[1].ToString());
Anyway the safest way is to create select statement with named colums instead of using *
Check that the value you are using for the username exists in the table.
You're also adding the same parameter twice. I don't know how the SqlCommand class will handle that and I can't test it right now, but I think it might be a good idea to clear your parameters (smd.Parameters.Clear()) between executions.
How can i execute a SELECT query from my Code Behind file and then iterate through it?
I want to do something like this (just a simple pseudo example):
// SQL Server
var results = executeQuery("SELECT title, name FROM table");
foreach (var row in results)
{
string title = row.title;
string name = row.name;
}
How can i do this within code?
Something like this:
string queryString =
"SELECT OrderID, CustomerID FROM dbo.Orders;";
using (SqlConnection connection = new SqlConnection(
connectionString))
{
SqlCommand command = new SqlCommand(
queryString, connection);
connection.Open();
SqlDataReader reader = command.ExecuteReader();
try
{
while (reader.Read())
{
Console.WriteLine(String.Format("{0}, {1}",
reader["OrderID"], reader["CustomerID"]));
}
}
}
Source: http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.aspx
The connectionString will vary depending on the Database product and the authentication mechanism used (Windows Auth, username/password, etc.). The example above assumes you are using SQL Server. For a complete list of different ConnectionStrings, go to http://www.connectionstrings.com/
This is going to be very simple I know. I have seen so many different ways of using sql in asp.net with no real standard. What I want to know is how to cleanly select from an sql database in asp.net and retrieve multiple records. For example: select all userids.
String sql =
"SELECT [UserId] FROM [UserProfiles] WHERE NOT [UserId] = 'CurrentUserId'";
string strCon = System.Web
.Configuration
.WebConfigurationManager
.ConnectionStrings["SocialSiteConnectionString"]
.ConnectionString;
SqlConnection conn = new SqlConnection(strCon);
SqlCommand comm = new SqlCommand(sql, conn);
conn.Open();
/*
This is where I need to know how to retrieve the information from the
above command(comm). I am looking for something similiar to php's
mysql_result. I want to access the records kind of like an array or some
other form of retrieving all the data.
Also when the new SqlCommand is called...does that actual run the
SELECT STATEMENT or is there another step.
*/
conn.Close();
I think that this is what you are looking for.
String sql = "SELECT [UserId] FROM [UserProfiles] WHERE NOT [UserId] = 'CurrentUserId'";
string strCon = System.Web
.Configuration
.WebConfigurationManager
.ConnectionStrings["SocialSiteConnectionString"].ConnectionString;
SqlConnection conn = new SqlConnection(strCon);
SqlCommand comm = new SqlCommand(sql, conn);
conn.Open();
SqlDataReader nwReader = comm.ExecuteReader();
while (nwReader.Read())
{
int UserID = (int)nwReader["UserID"];
// Do something with UserID here...
}
nwReader.Close();
conn.Close();
I do have to say, though, that the overall approach can use a lot of tuning. First, you could at least start by simplifying access to your ConnectionString. For example, you could add the following to your Global.asax.cs file:
using System;
using System.Configuration;
public partial class Global : HttpApplication
{
public static string ConnectionString;
void Application_Start(object sender, EventArgs e)
{
ConnectionString = ConfigurationManager.ConnectionStrings["SocialSiteConnectionString"].ConnectionString;
}
...
}
Now, throughout your code, just access it using:
SqlConnection conn = new SqlConnection(Global.ConnectionString);
Better yet, create a class in which the "plumbing" is hidden. To run the same query in my code, I'd just enter:
using (BSDIQuery qry = new BSDIQuery())
{
SqlDataReader nwReader = qry.Command("SELECT...").ReturnReader();
// If I needed to add a parameter I'd add it above as well: .ParamVal("CurrentUser")
while (nwReader.Read())
{
int UserID = (int)nwReader["UserID"];
// Do something with UserID here...
}
nwReader.Close();
}
This is just an example using my DAL. However, notice that there is no connection string, no command or connection objects being created or managed, just a "BSDIQuery" (which does lots of different things in addition to that shown). Your approach would differ depending on the tasks that you do most often.
Most of the time, I use this (note that I am also using a connection pooling approach):
public DataTable ExecuteQueryTable(string query)
{
return ExecuteQueryTable(query, null);
}
public DataTable ExecuteQueryTable(string query, Dictionary<string, object> parameters)
{
using (SqlConnection conn = new SqlConnection(this.connectionString))
{
conn.Open();
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = query;
if (parameters != null)
{
foreach (string parameter in parameters.Keys)
{
cmd.Parameters.AddWithValue(parameter, parameters[parameter]);
}
}
DataTable tbl = new DataTable();
using (SqlDataAdapter da = new SqlDataAdapter(cmd))
{
da.Fill(tbl);
}
return tbl;
}
}
}
Here's an adaption of your existing code:
String sql = "SELECT [UserId] FROM [UserProfiles] WHERE [UserId] != #CurrentUserId";
string strCon = System.Web
.Configuration
.WebConfigurationManager
.ConnectionStrings["SocialSiteConnectionString"].ConnectionString;
DataTable result = new DataTable();
using (var conn = new SqlConnection(strCon))
using (var cmd = new SqlCommand(sql, conn))
{
cmd.Parameters.Add("#CurrentUserID", SqlDbType.Int).Value = CurrentUserID;
conn.Open();
result.Load(cmd.ExecuteReader());
}
Creating a SqlCommand doesn't execute it at all.
The command will be executed when you call ExecuteReader or something similar.
If you want something which will fetch all the results into memory, you should be looking at DataSet/DataTable. There's a tutorial for them here - or there are plenty of others on the net, and any decent ADO.NET book will cover them too.
If you don't want to fetch them all into memory at once, then ExecuteReader it the method for you. That will return a SqlDataReader which is like a database cursor - it reads a row at a time, and you ask for individual columns as you want them, calling Read to get to the next row each time.
Whereas in PHP you'd do something like,
while ($row = mysql_fetch_array ($result))
{
//this assumes you're doing something with foo in loop
$foo = $row["userid"];
//using $foo somehow
}
in .NET, you do something different. Believe me, originating from a PHP background, the transition from PHP to .NET is not easy. There's a lot of things that will seem bizarre. After a while though, it will make sense! Just stick it out. I personally like it better.
Ok.. assuming you have a DataSet like you say, you can do something like this,
//assuming you have a DataSet called myDataSet
for (int i = 0; i < myDataSet.Tables[0].Rows.Count; i++)
{
//likewise assuming here you're doing something with foo in loop
string foo = myDataSet.Tables[0].Rows[i]["userid"].ToString();
//similarly do something with foo in loop
}
That does the same thing as the PHP snippet.