sql server - Why i can not handle the store procedure return value is c#? -

i'm new in c#,and want write simple application work sql server store procedure,in sql server write store procedure:

use [mammutrecruitment] alter procedure [dbo].[firststep]     @name nvarchar(max),@family nvarchar(max),@fathername nvarchar(max),@birthcertificate bigint,@placeofbirth nvarchar(max),@birthdate datetime,     @nationalcode bigint,@religion nvarchar(max),@faith nvarchar(max),@nationality nvarchar(max),@bloodgroup nvarchar(max) begin     declare @myid bigint     insert [dbo].[usermainspecifications] values(@name,@family,@fathername,@birthcertificate,@placeofbirth,1,@birthdate,@nationalcode,     @religion,@faith,@nationality,@bloodgroup,12,'123','123',1,2015-1-1,'12','123','1234',1)        select @myid=[userid] [mammutrecruitment].[dbo].[usermainspecifications]         [nationalcode]=@nationalcode         select @myid myid  end 

, in c# write code call that:

using (sqlconnection con = new sqlconnection("data source=.;initial catalog=mammutrecruitment;integrated security=true"))             {                 using (sqlcommand cmd = new sqlcommand("firststep", con))                 {                     cmd.commandtype = commandtype.storedprocedure;                     cmd.parameters.add("@name", sqldbtype.nvarchar).value = m.name;                     cmd.parameters.add("@family", sqldbtype.nvarchar).value = m.family;                     cmd.parameters.add("@fathername", sqldbtype.nvarchar).value = m.fathername;                     cmd.parameters.add("@birthcertificate", sqldbtype.bigint).value =convert.toint64(m.birthcertificate);                     cmd.parameters.add("@placeofbirth", sqldbtype.nvarchar).value = m.placeofbirth;                     cmd.parameters.add("@birthdate", sqldbtype.datetime).value =convert.todatetime(dt.tostring());                     cmd.parameters.add("@nationalcode", sqldbtype.bigint).value =convert.toint64(m.nationalcode);                     cmd.parameters.add("@religion", sqldbtype.nvarchar).value = m.religion;                     cmd.parameters.add("@faith", sqldbtype.nvarchar).value = m.faith;                     cmd.parameters.add("@nationality", sqldbtype.nvarchar).value = m.nationality;                     cmd.parameters.add("@bloodgroup", sqldbtype.nvarchar).value = m.bloodgroup;                     sqlparameter retval = cmd.parameters.add("@myid", sqldbtype.bigint);                     retval.direction = parameterdirection.returnvalue;                     con.open();                     cmd.executenonquery();                     var retunvalue = cmd.parameters["@myid"].value; 

in line 0 value always:

var retunvalue = cmd.parameters["@myid"].value; 

happen?how can solve problem?thanks.

this line:

    cmd.executenonquery(); 

is executing query , not returning value.

you start looking using instead:

 cmd.executereader(); 

or if want value of first field of first row, use this:

var returnvalue = cmd.executescalar(); 

which give object can convert or cast appropriate type method.