Jorgen,
Yes, I can see it now. I'm not sure if it's a bug or not, however.
You see, you're calling cmd.Prepare() before command is actually ready:
cmd.Parameters.Add("Ean",SqlDbType.NVarChar);
cmd.Prepare(); << Command is not ready yet: parameter value is not set.
cmd.Parameters[0].Value="5703919000189"; << Now value is set, but command
is already prepared so new value has no effect.
To fix the problem, do not call cmd.Prepare() at all or move this call
after command is actually ready:
cmd.Parameters.Add("Ean",SqlDbType.NVarChar);
cmd.Parameters[0].Value="5703919000189";
cmd.Prepare();
Thanks for reporting this problem. I will investigate to determine if it's
a bug or a by design behavior.
Best regards,
Ilya
This posting is provided "AS IS" with no warranties, and confers no rights.
--------------------
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>From: "Jorgen D." <(E-Mail Removed)>
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>Subject: RE: DataReader dosen't return row on the first call to Read
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>Hi Ilya.
>
>Thanks for your reply.
>
>I've also verified that it works as expected with the
>Northwind DB, when searching on ProductID which is an
>integer. But try search for a productname using
>SqlCeCommand cmd = new SqlCeCommand("SELECT productid from
>products where productname = ?",cn);
>When searching on VarChar fields you will experience the
>same "BUG"
>
>Kind regards
>Jorgen D.
>
>>-----Original Message-----
>>Jorgen,
>>
>>I've tried this with Northwind database and it works as
>expected.
>>Is there something special about your database?
>>
>>Best regards,
>>
>>Ilya
>>
>>This posting is provided "AS IS" with no warranties, and
>confers no rights.
>>
>>--------------------
>>>Content-Class: urn:content-classes:message
>>>From: "Jorgen D." <(E-Mail Removed)>
>>>Sender: "Jorgen D." <(E-Mail Removed)>
>>>Subject: DaraReader dosen't return row on the first call
>to Read
>>>Date: Fri, 12 Sep 2003 02:32:18 -0700
>>>Lines: 54
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>>>
>>>I'm using SqlCeDB and having troubels with prepared
>>>commands and the data reader.
>>>
>>>The first call to the Read method dosen't return a
>result,
>>>but recreating the reader, and call the read method
>again
>>>works as expected.
>>>
>>>Here is a sample, which will display 2 messagboxes. The
>>>first eith "Not Found" and the Second with "Found...".
>>>
>>>What am I dooing wrong ?
>>>
>>>Regards Joergen D.
>>>
>>>SqlCeConnection cn = new SqlCeConnection(@"Data
>Source=\My
>>>Documents\data.sdf");
>>>cn.Open();
>>>
>>>SqlCeCommand cmd = new SqlCeCommand("SELECT itemname
>from
>>>Stocktable where itemnumber = ?",cn);
>>>
>>>cmd.Parameters.Add("Ean",SqlDbType.NVarChar);
>>>cmd.Prepare();
>>>SqlCeDataReader dtr;
>>>
>>>// 1st try
>>>cmd.Parameters[0].Value="5703919000189";
>>>dtr = cmd.ExecuteReader(CommandBehavior.SingleRow);
>>>if (dtr.Read())
>>>{
>>> string s = dtr.GetString(0);
>>> MessageBox.Show("1. try - Found: "+s);
>>>}
>>>else
>>>{
>>> MessageBox.Show("1. try - Not Found");
>>>}
>>>dtr.Close();
>>>
>>>// 2nd try
>>>cmd.Parameters[0].Value="5703919000189";
>>>dtr = cmd.ExecuteReader(CommandBehavior.SingleRow);
>>>if (dtr.Read())
>>>{
>>> string s = dtr.GetString(0);
>>> MessageBox.Show("2. try - Found: "+s);
>>>}
>>>else
>>>{
>>> MessageBox.Show("2. try - Not Found");
>>>}
>>>
>>>dtr.Close();
>>>cn.Close();
>>>
>>
>>
>>.
>>
>
|
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