Re: Why is it neccesary to include SqlDbType to the SqlParameter?
From: Patrice (nobody_at_nowhere.com)
Date: 01/07/05
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Date: Fri, 7 Jan 2005 18:04:19 +0100
Thanks, interesting.
The length is used client side to truncate the string. If the length is not
known the string is sent entirely to the server that will eventuallty raise
the usual error when data doesn't fit the alloted space...
Patrice
--
"Greg Burns" <greg_burns@DONT_SPAM_ME_hotmail.com> a écrit dans le message
de news:OXsDJ8M9EHA.3588@TK2MSFTNGP10.phx.gbl...
> > Try to not specify the size and insert a long string in the DB. Is it
> > truncated ?
>
> No.
>
> I you try and insert a string longer than the field length without
> specifying the field length in the parameter it throws an exception!
> "System.Data.SqlClient.SqlException: String or binary data would be
> truncated."
>
> It does NOT throw the exception when you do specify the field length in
the
> parameter, it simpy truncates.
>
> Here is the code I tested with:
>
> Dim cn As New SqlConnection("data source=.;initial
> catalog=northwind;integrated security=SSPI;persist security
> info=False;packet size=4096;")
>
> Dim cmd As New SqlCommand("INSERT shippers (CompanyName, Phone)
> VALUES (@company_name, @phone)", cn)
>
> cmd.Parameters.Add("@company_name", SqlDbType.NVarChar).Value =
New
> String("X"c, 41) ' allows 40
> cmd.Parameters.Add("@phone", SqlDbType.NVarChar).Value = New
> String("Z"c, 25) ' allows 24
>
> Try
> cn.Open()
> cmd.ExecuteNonQuery()
> Catch ex As Exception
> Debug.WriteLine(ex.ToString)
> Finally
> If Not cn Is Nothing AndAlso cn.State = ConnectionState.Open
> Then cn.Close()
> End Try
>
>
> Out of curiosity I tried with a sproc also with the same results:
>
> CREATE PROCEDURE usp_InsertShipper
> @company_name nvarchar(40),
> @phone nvarchar(25)
>
> AS
>
> SET NOCOUNT ON
>
> INSERT shippers (CompanyName, Phone)
> VALUES (@company_name, @phone)
>
> Greg
>
>
> "Patrice" <nobody@nowhere.com> wrote in message
> news:eXA5lQC9EHA.3416@TK2MSFTNGP09.phx.gbl...
> > Try to not specify the size and insert a long string in the DB. Is it
> > truncated ?
> >
> > AFAIK it is valid to not specify a size for varchar when using
> > Transact-SQL.
> > In this case the default length is 30. It makes me think that the .NET
> > provider could do something similar...
> >
> > Thanks for letting us know what you find...
> >
> > Patrice
> >
> > --
> >
> > "Greg Burns" <greg_burns@DONT_SPAM_ME_hotmail.com> a écrit dans le
message
> > de news:OjgrJs28EHA.3012@TK2MSFTNGP09.phx.gbl...
> >> Replying to myself. :)
> >>
> >> > One of the overloads for creating a parameter is just the name and
> >> > type,
> >> > ommitting the size. I am not aware of any negative side affects of
> >> > this
> >> > for varchar (etc.) parameters. Anybody know?
> >>
> >> Just saw this in documentation:
> >>
> >> "The Size is inferred from the value of the dbType parameter if it is
not
> >> explicitly set in the size parameter."
> >>
> >> So what does this mean for a varchar?
> >>
> >> Greg
> >>
> >>
> >> "Greg Burns" <greg_burns@DONT_SPAM_ME_hotmail.com> wrote in message
> >> news:OWcTgo28EHA.3908@TK2MSFTNGP12.phx.gbl...
> >> >> It also seem annoying that every time I make a change in the
database
> >> >> (eg varchar(50) to varchar(100)), I have to check all my
> >> >> Sqlparameters. Is there a way to read these definitions from the
> >> >> stored procedure into the Sqlparameters?
> >> >
> >> > CommandBuilder has a DeriveParameters method (akin to the old ADO
> > refresh
> >> > method), but it is not recommended and will create an extra round
trip
> > to
> >> > the database.
> >> >
> >> > One of the overloads for creating a parameter is just the name and
> >> > type,
> >> > ommitting the size. I am not aware of any negative side affects of
> >> > this
> >> > for varchar (etc.) parameters. Anybody know?
> >> >
> >> > As for me, I have the same problem. I've been including the size,
and
> >> > then when it changes in the sproc, I gotta go change it in the code
> >> > too.
> >> > ;(
> >> >
> >> > As for your example; if you pass your DOB variable using the
> >> > SqlDbType.SmallDateTime you're not going to see a difference unless
the
> >> > precision of your DOB variable is to the second! Check out the SQL
> >> > datetime and smalldatetime datatypes in BOL for more info.
> >> >
> >> > Greg
> >> >
> >> > "Kenneth" <k.agerskov@get2net.dk> wrote in message
> >> > news:13664bff.0501050853.ff03210@posting.google.com...
> >> >> Can anyone explain me why it is neccesary to include SqlDbType to
the
> >> >> SqlParameter. In every example I see, it is done, but no one
explaines
> >> >> why.
> >> >>
> >> >> I have for example a date I want to save into my Sql Server database
> >> >> through a stored procedure-call. In the database it is defined as a
> >> >> SmallDateTime. Every 3 methods in the client-code below gives the
same
> >> >> (and correct) result. So why is it that important?
> >> >>
> >> >> dim param As SqlParameter
> >> >>
> >> >> 1. param = New SqlParameter("@DOB", SqlDbType.SmallDateTime)
> >> >> param.Value = textboxDOB
> >> >>
> >> >> 2. param = New SqlParameter("@DOB", SqlDbType.DateTime)
> >> >> param.Value = textboxDOB
> >> >>
> >> >> 3. param = New SqlParameter()
> >> >> param.ParameterName = "@DOB"
> >> >> param.Value = textboxDOB
> >> >>
> >> >> It also seem annoying that every time I make a change in the
database
> >> >> (eg varchar(50) to varchar(100)), I have to check all my
> >> >> Sqlparameters. Is there a way to read these definitions from the
> >> >> stored procedure into the Sqlparameters?
> >> >
> >> >
> >>
> >>
> >
> >
>
>
- Next message: Jason: "RE: Access Active Directory using .NET/ADO.NET"
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