在SSMS中正常运行时，为什么在c＃中调用存储过程会给出InvalidOperationException？

Question

I have the following method calling an SP from C# app:

public bool CheckEmail(string email)
    {
        bool success = false;
        string name;


            using (SqlConnection con = new SqlConnection(Internal_Audit_Capture.Properties.Settings.Default.Intenal_AuditDB))
            {
                con.Open(); 
                try
                {
                    using (SqlCommand command = new SqlCommand("IntAudit.p_checkEmail", con))
                    {


                        command.CommandType = CommandType.StoredProcedure;
                        command.Parameters.Add(new SqlParameter("@email", maskedTextBox1.Text.Trim()));
                        command.Parameters.Add("@success", SqlDbType.Bit).Direction = ParameterDirection.Output;
                        command.Parameters.Add("@name", SqlDbType.VarChar).Direction = ParameterDirection.Output;
                        command.ExecuteNonQuery();
                        success = (bool)command.Parameters["@success"].Value;
                        name = (string)command.Parameters["@name"].Value;
                    }

                    return success;
                }

                catch (Exception ex)
                {
                    MessageBox.Show(ex.ToString());
                    return success;
                }
            }
    }

p_checkEmail queries the following table:

[IntAudit].[LOGINDETAILS](
[ID] [int] IDENTITY(1,1) NOT NULL,
[NAME] [varchar](30) NOT NULL,
[PASSWORD] [nvarchar](30) NOT NULL,
[ADMIN] [bit] NULL,
[EMAIL] [varchar](50) NOT NULL,PRIMARY KEY CLUSTERED ([ID] ASC))

And it's code is:

create procedure IntAudit.p_checkEmail
@email varchar(50),
@success bit OUTPUT,
@name varchar(30) OUTPUT
as

set nocount on;

if(exists(select 1 from [IntAudit].[LOGINDETAILS] where [EMAIL] = @email))
 begin
  select @name = [NAME] from [IntAudit].[LOGINDETAILS] where [EMAIL] = @email
  set @success = 1
  return
 end
else
 begin
  set @name = null
  set @success = 0
  return
 end

go

Running the checkEmail method gives a System.InvalidOperationException: String[2]: size property has invalid size of 0 error. Executing the procedure in SSMS runs fine though. The method is mean't to check for an email address in the table and return the username, if the address entered by the user exists. I have tried changing the data types but I still get the same error. Is there anything I am missing?

EDIT: Exception Details:

System.InvalidOperationException: String[2]: the Size property has an invalid size of 0.

at System.Data.SqlClient.SqlParameter.Validate(Int32 index, Boolean isCommandProc)

at System.Data.SqlClient.SqlCommand.SetUpRPCParameters(_SqlRPC rpc, Int32 startCount, Boolean inSchema, SqlParameterCollection parameters)

at System.Data.SqlClient.SqlCommand.BuildRPC(Boolean inSchema, SqlParameterCollection parameters, _SqlRPC& rpc)

at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds)

at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite)

at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, String methodName, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite)

at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()

at Internal_Audit_Capture.ForgotPassword.CheckEmail(String email) in C:\\Internal Audit\\Internal Audit Capture\\Internal Audit Capture\\ForgotPassword.cs:line 41

Answer 1

您需要指定@name参数的大小。

command.Parameters.Add("@name", SqlDbType.VarChar, 30).Direction = ParameterDirection.Output;

Answer 2

Try this

command.Parameters.Add("@email", SqlDbType.VarChar).Value = maskedTextBox1.Text.Trim();

instead of

command.Parameters.Add(new SqlParameter("@email", maskedTextBox1.Text.Trim()));