C# and SQL types

[Techno]

Hi there, this is a similar Q as my other thread but not the same...

What I am wondering is, in SQL we can stores binary. And in C# we have to make byte[] object and then send that value stored in the byte[] paramater to SQL and its stored.

but when RETRIEVING from SQL using dataReader, and that value to retrieve is of SQL binary.... what type should I use in order to retrieve the value?

i.e:

object theDataReadFromSQL;

while(dataReader.Read())
{
   theDataReadFromSQL = dataReader.GetValue(0);
}

thats fine but the thing is, I cannot compare the bytes with the bytes of something else, as the bytes stored in theDataReadFromSQL is of type object.

its hard to explain... but i hope you understand...?

[DeadEyes]

I've never had to use it but the DataReader has a GetBytes method. Would that not be more appropriate method than GetValue

[Techno]

I remember looking at it however I do not know what parameters to give it....

what should i give the parameters? I do not understand the last 3/4 of them...

[DeadEyes]

theres an example here of reading and writing blobs

[Techno]

thanks, im just trying it but tryin to figure out how to compare the long bytes value given from SQL to the bytes calculated from the textbox on the form...

[edit]
Just tried that suggestion, its not giving me the thing i want, it gives me the length of the value retrieved. maybe you misunderstood what I said?
[/edit]

[Techno]

currently I have a way but the thing is im using object type to get the value from SQL using dataReader.GetValue(0) then compare that with the object value of bytes of the textbox - gets me the correct bytes but the one on the textbox is less than 50 chars... anythin from sql will be of length 50 chars.

I dont want to have to do an unprofessional string concat stuff to make the value of length 50 chars

[DeadEyes]

[edit]
Just tried that suggestion, its not giving me the thing i want, it gives me the length of the value retrieved. maybe you misunderstood what I said?
[/edit]

byte outbyte[] = new byte[50];
retval = myReader.GetBytes(1, 0, outbyte, 0, 50);

retval stores the number of bytes read.
outbyte stores the actual data.

[Techno]

excellent! thanks for this

but now... to somehow make the bytes value contained in the textbox the same length as outbyte[]

[DeadEyes]

you could try an Array.Copy
byte[] dest = new byte[50]
Array.Copy(source,0,dest,0,source.Length);

[Techno]

thanks

looks good but when i do an if statement like this, its always returned as false!

if(dest == source)
{
}
else
{
//always goes here!
}

but I have looked at both of the values and both are the same! Same result occurs if I do a .Equals()

[DeadEyes]

AFAIK == and Equals compare references unless the class overides them so that they explicitly perform a comparsion on the contents.
I guess a loop is needed to check each item.