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Why only one character is returned?
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À
26/05/2012 03:50:21
Information générale
Forum:
ASP.NET
Catégorie:
Autre
Versions des environnements
Environment:
C# 2.0
Divers
Thread ID:
01544467
Message ID:
01544506
Vues:
29
>>Hi,
>>
>>This is a continuation of the thread where I am trying to get the value of OUTPUT parameter when calling a stored procedure. The stored procedure is very simple and has one OUTPUT parameter where the value is set to something like 'ABCD' (I tried, '1234', and so on).
>>
>>The problem is that the code below, when gets the value of parameter only shows 1 character. E.g. 'A' or '1', and so on.
>>
>>Here is the summary of the code (basically copy of what Viv suggested in the other thread):
>>
>> System.Data.Common.DbCommand command = new SqlCommand();
>> System.Data.IDbDataParameter p = command.CreateParameter();
>> p.ParameterName = "@Param3";
>> p.Direction = ParameterDirection.Output;
>> p.Value = cVal3;
>> command.Parameters.Add(p);
>>int RetValue = command.ExecuteNonQuery()
>> var v = command.Parameters["@Param3"].Value;
>>// the value 'v' has 'A' or '1' but never the entire string
>>
>>
>>Do you see where could be the problem? TIA.
>
>You missed out the most important line. Snip:
>p.Direction = ParameterDirection.Output;
>//etc  <------- This one :-}
>p.Value = cVal3;
I think you have this working now anyway but here's a complete example. Given
CREATE PROCEDURE [dbo].[MyProc]
>   @Param3  nvarchar(30) OUT
>AS
>BEGIN
>   SET @Param3 = 'Hello ' + @Param3
>   RETURN
>END
Then
            SqlConnection conn = new SqlConnection();
>            conn.ConnectionString = s;
>            conn.Open();
>
>            System.Data.Common.DbCommand command = new SqlCommand();
>            System.Data.IDbDataParameter p = command.CreateParameter();
>
>            p.ParameterName = "@Param3";
>            p.Direction = ParameterDirection.InputOutput;
>            p.Value = "World";
>            p.DbType = System.Data.DbType.String;
>            p.Size = 30;
>            command.Parameters.Add(p);
>
>            command.Connection = conn;
>            command.CommandType = System.Data.CommandType.StoredProcedure;
>            command.CommandText = "MyProc";
>            command.ExecuteNonQuery();
>            string result = (string) command.Parameters["@Param3"].Value;
Yes, I see that I missed specifying the Size of the passed parameter. Once I added this (Size) the code works. Except (I have not tested it today) yesterday the call to ExecuteNonQuery() was returning -1. Maybe it is normal but I thought it should be 0. I will recheck.

One other question I have. I see that you specified ParameterDirection as .InputOutput. Why not only .Output?

Thank you very much for your help.
"The creative process is nothing but a series of crises." Isaac Bashevis Singer
"My experience is that as soon as people are old enough to know better, they don't know anything at all." Oscar Wilde
"If a nation values anything more than freedom, it will lose its freedom; and the irony of it is that if it is comfort or money that it values more, it will lose that too." W.Somerset Maugham
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