5c6253a7
XPost: microsoft.public.dotnet.languages.csharp
From: arne@vajhoej.dk
On 31-07-2010 22:15, Joe Cool wrote:
> On Jul 31, 10:04 pm, Arne Vajhøj wrote:
>> On 31-07-2010 21:52, Joe Cool wrote:
>>> On Jul 31, 9:46 pm, Arne Vajhøj wrote:
>>>> On 31-07-2010 21:41, Joe Cool wrote:
>>
>>>>> On Jul 31, 9:21 pm, Arne Vajhøj wrote:
>>>>>> On 31-07-2010 20:50, Joe Cool wrote:
>>>>>>> On Jul 31, 8:41 pm, Arne Vajhøj wrote:
>>>>>>>> On 31-07-2010 20:39, Joe Cool wrote:
>>>>>>>>> On Jul 31, 8:37 pm, Arne Vajhøj wrote:
>>>>>>>>>> On 31-07-2010 20:29, Joe Cool wrote:
>>
>>>>>>>>>>> On Jul 31, 8:02 pm, Arne Vajhøj wrote:
>>>>>>>>>>>> On 31-07-2010 19:36, Joe Cool wrote:
>>
>>>>>>>>>>>>> I am cross posting this request for help in both the C#,NET and
the
>>>>>>>>>>>>> SQLServer newsgroups in he hope that some reader of one these
>>>>>>>>>>>>> newsgroups can offer some help.
>>
>>>>>>>>>>>>> I am well aware that the image datatype (as well as others) are
being
>>>>>>>>>>>>> phased out in some future version of SQL Server. For that
reason, in
>>>>>>>>>>>>> all of my personal C#.NET projects that store images use the
>>>>>>>>>>>>> varbinary(max) datatype.
>>
>>>>>>>>>>>>> I am in the process of converting a VB.NET project that I use for
>>>>>>>>>>>>> consulting work with a former (and hopefully soon to be repeat)
>>>>>>>>>>>>> employer tp C#.NET. When originally designed, their software was
based
>>>>>>>>>>>>> on SQL7. Currently their software supports SQL2005. One key
table in
>>>>>>>>>>>>> their database is a table of images and (not sure if it still
does)
>>>>>>>>>>>>> but legacy databases utilize the image datatype to store images.
With
>>>>>>>>>>>>> SQL7 I used a SQL command line utility called TEXTCOPY to
extract the
>>>>>>>>>>>>> binary content of image columns to a JPG file.
>>
>>>>>>>>>>>>> This utility needs to be able to extract these images to external
>>>>>>>>>>>>> files even for legacy databases that may still use the image
datatype.
>>>>>>>>>>>>> But I find that the technique I use to extract images from a
>>>>>>>>>>>>> varbinary(max) column doesn't work for image datatypes. And I
see that
>>>>>>>>>>>>> SQL2005, while it still supports image datatype, the TEXTCOPY
utility
>>>>>>>>>>>>> is nowhere to be found.
>>
>>>>>>>>>>>>> Any ideas on how to extract image data types from a SQL2005
database
>>>>>>>>>>>>> with C#.NET?
>>
>>>>>>>>>>>> Have you tried the obvious: SqlConnection, SqlCommand, SELECT,
>>>>>>>>>>>> ExecuteReader, SqlDataReader og læse kolonnen som byte[] ?
>>
>>>>>>>>>>> Here is what I am using that works with varbinary(max) datatype
>>>>>>>>>>> columns.
>>
>>>>>>>>>>> SqlCommand cmd;
>>>>>>>>>>> SqlDataReader rdr;
>>>>>>>>>>> DataTable dataTable;
>>
>>>>>>>>>>> cmd = new SqlCommand("select imagecolumn, linkcolumn from images",
>>>>>>>>>>> cn)'
>>>>>>>>>>> rdr = cmd.ExecuteReader();
>>>>>>>>>>> dataTable.Load(rdr);
>>
>>>>>>>>>> Drop the data table and try:
>>
>>>>>>>>>> while(rdr.Read())
>>>>>>>>>> {
>>>>>>>>>> byte[] image = (byte[])rdr[0];
>>>>>>>>>> string link = (string)rdr[1];
>>>>>>>>>> // process image and link
>>
>>>>>>>>>> }
>>
>>>>>>>>> Umm, so are you saying that while the datatable works with a
>>>>>>>>> varbinary(max) datatype, for an image datatype I should drop the
>>>>>>>>> datatable and just use a data reader?
>>
>>>>>>>> I don't know if the data table is the problem.
>>
>>>>>>>> I know that the reader will work.
>>
>>>>>>>> And according to your description, then you don't need
>>>>>>>> the data table.
>>
>>>>>>>> So it is worth a try.
>>
>>>>>>> The only reason I was trying to use a data table is because I am using
>>>>>>> a support class library (that I also wrote) that returns data using
>>>>>>> just a datatable. I suppose I can enhance it to also support returning
>>>>>>> data with a data reader.
>>
>>>>>> What is the problem when you try getting the image with the
>>>>>> current code?
>>
>>>>> The extracted files are smaller than the JPGs extracted by the VB.NET
>>>>> version and are not valid JPG files (their content is not the same).
>>
>>>> Is the size in the DB correct?
>>
>>>> If yes - is the size in the data table correct?
>>
>>> In the FileStream object's Write mthod, I am using
>>> ((byte[])dataTable.Rows[i][0]).Length as the number of bytes to write.
>>
>>> I assume thelength is the DB is correct since I am using the same DB
>>> to test the C#.NET program to test with that I originally used the
>>> VB.NET programs to originally extract the JPs with.
>>
>> How does the VB.NET and C# code differ?
>
> I already posted the C#.NET code. The VB.NET code (as my original post
> mentioned) used the now (apparent) non-existant TEXTCOPY command line
> utility.
Can you create a complete example that illustrates the problem.
Basically it should work.
Here is a copy of some old code of mine:
SqlCommand ins = new SqlCommand("INSERT INTO imgtest
VALUES(@id,@img)", con);
ins.Parameters.Add("@id", SqlDbType.Int);
ins.Parameters.Add("@img", SqlDbType.Image);
ins.Parameters["@id"].Value = 1;
ins.Parameters["@img"].Value = imgdata;
ins.ExecuteNonQuery();
...
SqlCommand sel = new SqlCommand("SELECT img FROM imgtest WHERE
id = @id", con);
sel.Parameters.Add("@id", SqlDbType.Int);
sel.Parameters["@id"].Value = 1;
byte[] imgdata2 = (byte[])sel.ExecuteScalar();
Arne
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