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How can i get #rErr / Output Parameter value in c#?

I create a SQL stored procedure
create proc p1
(
#name1 nvarchar(50),
#rErr int OUTPUT
)
as
begin Transaction
insert into test (name1)
values (#name1)
if #name1 = 'n100'
Begin
Rollback Transaction
Set #rErr=50001
Return #rErr
End
commit Transaction
How can I get the #rErr value in C#?

Accessing output parameters is a little awkward; you need to add them to the parameters collection in the usual way, with with a .Direction of Output. Then you can read the .Value of the parameter object after executing the method. However: it is much easier to use select and process it as a result. Note that return values can be done in a similar way, but with the appropriate .Direction. The fact that you both output and return it, in this case, makes it even more fun... I'd just use the output part, personally. Or ... throw an exception (raiserrror).
Something like:
using (var cmd = conn.CreateCommand())
{
cmd.CommandText = "p1";
cmd.CommandType = CommandType.StoredProcedure;
var name = cmd.CreateParameter();
name.ParameterName = "#name1";
name.Value = "abc"; // etc
cmd.Parameters.Add(name);
var err = cmd.CreateParameter();
err.ParameterName = "#rErr";
err.Direction = ParameterDirection.Output;
cmd.Parameters.Add(err);
cmd.ExecuteNonQuery();
if (err.Value is int i)
{
// error i happened
}
}
However: if you'd just used:
raiserror (50001, 16, 1) -- severity needs to be at least 16 here; typically = 16
or (in more recent SQL Server versions):
throw 50001, 'oops', 1
you can get a similar result much more easily; this will result in an Exception direction from the ADO.NET layer.
(note that you should add the custom error message formally to sysmessages when using raiserror - throw doesn't require that step)
If you used the throw (or raiserror) approach, and removed the output parameter, this entire piece of code could become, with some help from Dapper:
conn.Execute("p1", new { name1 = "abc" }, commandType: CommandType.StoredProcedure);
which is a lot easier to get right!

You don't need transaction for a single insert, you can refactor your SP like following. To return the code as output parameter, you can simply use RETURN(50001)
CREATE PROC P1 (#name1 NVARCHAR(50),
#rErr INT output)
AS
IF #name1 <> 'n100'
BEGIN
INSERT INTO test(name1)
VALUES (#name1)
RETURN(0)
END
RETURN(50001)

Execute One SQL Block Without Interruption

Say I have the following SQL statements that I'm executing using ExecuteNonQuery(DbCommand) from C# in a Web Application
DECLARE #InsertedProductID INT -- this is passed as a parameter
DECLARE #GroupID INT -- this is passed as a parameter
DECLARE #total INT
SET #total = (SELECT COUNT (*) FROM Products WHERE GroupID = #GroupID)
UPDATE Products SET ProdName = 'Prod_'+ CAST(#total as varchar(15))
WHERE ProductID = #InsertedProductID
My problem is that I want to ensure that the whole block executes at one. My goal is to always have the ProdName unique per group. If I leave everything the way it is, there is a good chance that I will get duplicate product names if an insert took place in between getting the #total and performing the UPDATE. Is there a way to make sure that the whole SQL block executes at once with no interruption. Will exec or sp_executesql achieve this? My last resort would be to put a lock around the ExecuteNonQuery(DbCommand) But I don't like that since it would create a bottleneck. I don't think that using a sql transaction is helpful here because I'm not worried about the integrity of the commands, I'm rather worried about the parallelism of the commands.

Generally any DML statement (UPDATE/INSERT/DELETE) places a lock (row level / table level) on the particular table but if you want to explicitly guarantee that your operation shouldn't interfere with other executing statement then you should consider placing that entire SQL block inside a transaction block saying
Begin transaction
begin try
DECLARE #InsertedProductID INT -- this is passed as a parameter
DECLARE #GroupID INT -- this is passed as a parameter
DECLARE #total INT
SET #total = (SELECT COUNT (*) FROM Products WHERE GroupID = #GroupID)
UPDATE Products SET ProdName = 'Prod_'+ CAST(#total as varchar(15)) WHERE ProductID = #InsertedProductID
commit; // commits the transaction
end try
begin catch
rollback; //Rolls back the transaction
end catch
end
You should also consider making the Transaction Isolation Level to READ COMMITTED to avoid dirty reads. Also, obviously you should wrap this entire logic in a stored procedure rather executing them as adhoc SQL

If you have control of the creation of your SqlConnection objects, consider relying on database locks using Transactions and an appropriate IsolationLevel. Using Snapshot, for example, will cause the second transaction committed to fail if a separate transaction touched the data before the commit occurred.
Something like:
var c = new SqlConnection(...);
var tran1 = c.BeginTransaction(IsolationLevel.Snapshot);
var tran2 = c.BeginTransaction(IsolationLevel.Snapshot);
DoStuff(c, tran1);//Touch some database data
tran1.Commit();
DoStuff(c, tran2);//Change the same data
tran2.Commit();//Error!

not so sure you could not just do this
UPDATE Products
SET ProdName = 'Prod_'+ CAST((SELECT COUNT (*)
FROM Products
WHERE GroupID = #GroupID) as varchar(15))
WHERE ProductID = #InsertedProductID
But to me that is an odd update

Using a transaction is the right way to go. Along with the other answers, you can also use TransactionScope. The TransactionScope implicitly enrolls the connection and SQL command(s) into a transaction. A rollback will happen automatically if there is an issue since the TransactionScope is in a using block.
Example:
try
{
using (var scope = new TransactionScope())
{
using (var conn = new SqlConnection("your connection string"))
{
conn.Open();
var cmd = new SqlCommand("your SQL here", conn);
cmd.ExecuteNonQuery();
}
scope.Complete();
}
}
catch (TransactionAbortedException ex)
{
}
catch (ApplicationException ex)
{
}

How execute a stored procedure from the web method?

I want to execute a stored procedure inside a Web Method. It is a select statement in the stored procedure. I tried with the following code. However, the result not successful. The result should return 1 but it is always returning -1. Does anyone have any idea? Please help.
Here is the web service .asmx code:
public class retrieveLoan : System.Web.Services.WebService
{
string constring = "Data Source=DIT-NB1260382;Initial Catalog=Experiment;Integrated Security=True";
SqlConnection myConn;
[WebMethod(Description="Simple Example")]
public int GetResult(int id, int age)
{
Int32 numberofRecords = 0;
System.Data.DataSet workDS = new System.Data.DataSet();
SqlCommand objCommand = default(SqlCommand);
//Create a command object
objCommand = new SqlCommand();
//prepare the command for retreiving
objCommand.CommandType = System.Data.CommandType.StoredProcedure;
objCommand.CommandText = "myprocedure2";
//open the connection
myConn = new SqlConnection(constring);
myConn.Open();
objCommand.Connection = myConn;
try
{
numberofRecords = (Int32)objCommand.ExecuteScalar();
return numberofRecords;
}
catch (Exception)
{
return -1;
}
finally
{
myConn.Close();
}
}
}
and my store procedure:
ALTER PROCEDURE [dbo].[myprocedure2]
(
#puserid int,
#page int
)
AS
BEGIN
select * from userdet where userid = #puserid and age = #page
END

I believe that executing this stored procedure without parameters would return an exception.
First of all, for you to see the Exception, in the catch declaration, you should try and declare the Exception explicitly, like this:
try
{
numberofRecords = (Int32)objCommand.ExecuteScalar();
return numberofRecords;
}
catch (Exception ex)
{
//here you can enter into debug mode and see the exception "ex"
return -1;
}
finally
{
myConn.Close();
}
When you see the exception, you can quickly solve the problem.
Next, you should add the parameters as NULL into your stored procedure (so they can accept null values), OR, if you do not, you must add these parameter in C# code, and send them some values.
Also, i would like to point the fact that if you want to retrieve a COUNT, you should modify your stored procedure as following:
ALTER PROCEDURE [dbo].[myprocedure2] ( #puserid int, #page int )
AS
BEGIN
select COUNT(userid) from userdet where userid = #puserid and age = #page
END
Hope this solves your issues here.

You're not providing a lot of info, so hard to answer, but here's a way forward:
Change catch (Exception) into catch (Exception ex), then see what that exception contains, either by returning it, or by analyzing it in debug mode.
If you publish your project in debug mode, you can connect to it and debug it using Tools > Attach to Process and connect to the process called w3wp.exe (if there are more than one of them, look for the one with the correct version of .Net under the Type-column).

Your query is "select * from userdet". What ExecuteScalar() does is pick the first cell value. Now you are type casting this to int. if your first cell value is a string type or some other type. you will definitely receive a error. And that will return -1. Please define the column name in your select query or count like this "select count(*) from userdet". Check ur query.

Output variable not getting set in SQL Server stored procedure

I hope this is not one of those questions where I slap myself afterwards, but this is really confusing me. I have this working for another one of my stored procedures which is why this is so confusing. It's basically the same setup in both. Here's what's happening.
Here's an example of my stored procedure:
ALTER PROCEDURE [dbo].[CreateRecord]
-- Add the parameters for the stored procedure here
#Link1Id INT = NULL,
#Link2Id INT = NULL,
#Amount MONEY,
#Output int out
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
SET #Output = 0
-- Insert statements for procedure here
IF #Link1Id = NULL
BEGIN
IF NOT EXISTS(SELECT * FROM dbo.Records WHERE Link2Id = #Link2Id)
INSERT INTO [dbo].[Records]
([Link1Id]
,[Link2Id])
VALUES
(#Link1Id
,#Link2Id)
SET #Output = (SELECT RecordId FROM dbo.Records WHERE Link2Id = #Link2Id)
END
ELSE
BEGIN
IF NOT EXISTS(SELECT * FROM dbo.Records WHERE Link1Id = #Link1Id)
INSERT INTO [dbo].[Records]
([Link1Id]
,[Link2Id])
VALUES
(#Link1Id
,#Link2Id)
SET #Output = (SELECT RecordId FROM dbo.Records WHERE Link1Id = #Link1Id)
END
END
Now, I have created a unit test that basically runs this procedure, and tries to Assert that the returned #Output is greater than 0, but the #Output parameter never has a value on the SqlCommand in the code. Here's some of the C# code:
private int ExecuteNonQueryWithOutput(string procedureName, SqlParameter[] parameters)
{
SqlCommand command = this.GenerateCommand(procedureName, parameters);
connection.Open();
command.ExecuteNonQuery();
int retval = (int)command.Parameters[OUTPUT].Value;
connection.Close();
return retval;
}
Now, I can step over the line that calls ExecuteNonQuery(), and verify in the database that the new (and correct) record is there, but then on the next line, it throws an exception when it calls (int)command.Parameters[OUTPUT].Value; as the Value is not there.
This is working perfectly for another procedure that I have which is setup in the same exact fashion. Do you know why it wouldn't be working here?
Thanks, I'm kind of stumped. I've debugged for a while now with no luck.
Edit:
Code that generates the parameters array:
List<SqlParameter> parameters = new List<SqlParameter>();
parameters.Add(new SqlParameter { ParameterName = "#Link1Id", SqlDbType = SqlDbType.Int, Direction = ParameterDirection.Input, Value = link1Val });
parameters.Add(new SqlParameter { ParameterName = "#Link2Id", SqlDbType = SqlDbType.Int, Direction = ParameterDirection.Input, Value = link2Val });
parameters.Add(new SqlParameter { ParameterName = OUTPUT, SqlDbType = SqlDbType.Int, Direction = ParameterDirection.Output });
return this.ExecuteNonQueryWithOutput("CreateRecord", parameters.ToArray());

I don't see where you've declared #Output. Did you mean:
ALTER PROCEDURE [dbo].[CreateRecord]
-- Add the parameters for the stored procedure here
#Link1Id INT = NULL,
#Link2Id INT = NULL,
#Amount MONEY,
#Output INT = NULL OUTPUT
AS
Also I'm not 100% sure you have the syntax right for retrieving a named output parameter. But the parameter has to exist before you can reference it anyway. How did you save that stored procedure without declaring #Output?

There are numerous things wrong with the code that go beyond the output parameter issue.
To answer the actual question, you are likely passing a NULL value back as the Output. When it tries to convert this to an Int you are getting an error.
Also the sql line:
IF #Link1ID = null
Will ALWAYS fail. In SQL parlance, null is an indeterminate value, so (null != null). The way to test for null values is to use IS. For example:
IF (#Link1ID is null)
Which leads me to believe that you are actually getting a primary key violation in the sql code.
Now, onto the bigger issue. Your C# code is flawed. The command object is never disposed of and if there are any issues your connection object won't be disposed of either. This will lead to fun sql errors due running out of available sql connections..
It should look something like the following:
private int ExecuteNonQueryWithOutput(string procedureName, SqlParameter[] parameters)
{
int retval = 0;
using (SqlConnection conn = new SqlConnection("connection string here"))
using (SqlCommand command = this.GenerateCommand(procedureName, parameters)) {
connection.Open();
command.ExecuteNonQuery();
retval = (int)command.Parameters[OUTPUT].Value;
}
return retval;
}
Note that this declares, uses and disposes of your connection and command objects locally. If there is a problem this will make sure the resources are properly disposed of.
Also note that it does not use a global "connection" object. Connection pooling offered by the operating system is incredibly efficient at opening/closing connections as needed. Because of this the best practice is to instantiate and keep them around only long enough to deal with the current operation. The longer it's open the more likely you'll run into issues.

"connection has been disabled" error message when quickly creating/deleting databases

Introduction
I'm writing a web application (C#/ASP.NET MVC 3, .NET Framework 4, MS SQL Server 2008, System.Data.ODBC for database connections) and I'm having quite some issues regarding database creation/deletion.
I have a requirement that application should be able to create and delete databases.
Problem
Application fails stress testing for that function. More specifically, if client starts to quickly create, delete, create again a database with the same name then eventually (~on 5th request) server code throws ODBCException 'Connection has been disabled.'. This behavior is observed on all machines that test has been performed on - the exact failing request may be not 5th but somewhere around that value.
Research
Googling on exception gave very low output - the exception seems very generic one and no analogue issues found. One of suggestions I've found was that my development Windows 7 might not be able to handle numerous simultaneous connections as it's not Server OS. I've tried installing our app on Windows 2008 Server - almost no change in behavior, just a bit more requests processed before exception occurs.
Code and additional comments on implementation
Databases are created using stored procedure like this:
CREATE PROCEDURE [dbo].[sp_DBCreate]
...
#databasename nvarchar(124) -- 124 is max length of database file names
AS
DECLARE #sql nvarchar(150);
BEGIN
...
-- Create a new database
SET #sql = N'CREATE DATABASE ' + quotename(#databasename, '[');
EXEC(#sql);
IF ##ERROR <> 0
RETURN -2;
...
RETURN 0;
END
Databases are deleted using the following SP:
CREATE PROCEDURE [dbo].[sp_DomainDelete]
...
#databasename nvarchar(124) -- 124 is max length of database file names
AS
DECLARE #sql nvarchar(200);
BEGIN
...
-- check if database exists
IF EXISTS(SELECT * FROM [sys].[databases] WHERE [name] = #databasename)
BEGIN
-- drop all active connections
SET #sql = N'ALTER DATABASE' + quotename(#databasename, '[') + ' SET SINGLE_USER WITH ROLLBACK IMMEDIATE';
EXEC(#sql);
-- Delete database
SET #sql = N'DROP DATABASE ' + quotename(#databasename, '[');
EXEC(#sql);
IF ##ERROR <> 0
RETURN -1; --error deleting database
END
--ELSE database does not exist. consider it deleted.
RETURN 0;
END
In both SPs I've skipped less relevant parts like sanity checks.
I'm not using any ORMs, all SPs are called from code by using OdbcCommand instances. New OdbcConnection is created for each function call.
I sincerely hope someone might give me clue to the problem.
UPD: The exactly same problem occurs if we just rapidly create a bunch of databases. Thanks to everyone for suggestions on database delete code, but I'd prefer to have a solution or at least a hint for more general problem - the one which occurs even without deleting DBs at all.
UPD2: The following code is used for SP calls:
public static int ExecuteNonQuery(string sql, params object[] parameters)
{
try
{
var command = new OdbcCommand();
Prepare(command, new OdbcConnection( GetConnectionString() /*irrelevant*/), null, CommandType.Text, sql,
parameters == null ?
new List<OdbcParameter>().ToArray() :
parameters.Select(p => p is OdbcParameter ? (OdbcParameter)p : new OdbcParameter(string.Empty, p)).ToArray());
return command.ExecuteNonQuery();
}
catch (OdbcException ex)
{
// Logging here
throw;
}
}
public static void Prepare(
OdbcCommand command,
OdbcConnection connection,
OdbcTransaction transaction,
CommandType commandType,
string commandText,
params OdbcParameter[] commandParameters)
{
if (connection.State != ConnectionState.Open)
{
connection.Open();
}
command.Connection = connection;
command.CommandText = commandText;
if (transaction != null)
{
command.Transaction = transaction;
}
command.CommandType = commandType;
if (commandParameters != null)
{
command.Parameters.AddRange(
commandParameters.Select(p => p.Value==null &&
p.Direction == ParameterDirection.Input ?
new OdbcParameter(p.ParameterName, DBNull.Value) : p).ToArray());
}
}
Sample connection string:
Driver={SQL Server}; Server=LOCALHOST;Uid=sa;Pwd=<password here>;

Okay. There may be issues of scope for OdbcConnection but also you don't appear to be closing connections after you've finished with them. This may mean that you're reliant on the pool manager to close off unused connections and return them to the pool as they timeout. The using block will automatically close and dispose of the connection when finished, allowing it to be returned to the connection pool.
Try this code:
public static int ExecuteNonQuery(string sql, params object[] parameters)
{
int result = 0;
try
{
var command = new OdbcCommand();
using (OdbcConnection connection = new OdbcConnection(GetConnectionString() /*irrelevant*/))
{
connection.Open();
Prepare(command, connection, null, CommandType.Text, sql,
parameters == null ?
new List<OdbcParameter>().ToArray() :
parameters.Select(p => p is OdbcParameter ? (OdbcParameter)p : new OdbcParameter(string.Empty, p)).ToArray());
result = command.ExecuteNonQuery();
}
}
catch (OdbcException ex)
{
// Logging here
throw;
}
return result;
}