this is to all who have responded so far: thanks so
much for your help so far: as a caveat, i am new to
SQL so bear with me..
here is my code from the main.cpp where i build the
short array:
ostringstream insert;
unsigned short *blobarray = new unsigned short[10];
//for simple purposes i will make this a small array.
for(int i = 0; i < 10; i++)
blobArray[i] = i * 3;
insert << "insert into Images values(NULL, '" << Hello
World << "')"
long ID = db.performUpdate(insert2.str(), blobarray,
10);
...........outside of main.........
long performUpdate(string update, const unsigned short
* buffer, unsigned long size)
{
sqlite3_stmt *statement;
open(filename); //this simply opens the db file,
nothing big
int status = sqlite3_prepare_v2(db, update.c_str(),
-1, &statement, NULL);
if((status != SQLITE_OK) || (statement == NULL))
cout << "error preparing" << endl;
else cout << "preparing SQL statement successful" <<
endl;
status = sqlite3_bind_blob(statement, 1, buffer,
size * sizeof(unsigned short), SQLITE_STATIC);
if(status != SQLITE_OK)
cout << "status: " << status << " error binding
blob. " << endl;
else cout << "binding blob successful" << endl;
while((status = sqlite3_step(statement)) ==
SQLITE_ROW);
//check for status error like above
status = sqlite3_finalize(statement);
//check for status error like above
// other non sqlite stuff......
} //end performUpdate
do i need to create a column in table Images for the
blob? or does this happen automatically? right now i
have:
create tables Images(ImageID integer primary key,
messageID text not null);
do i have to anything here for the blob?
i might have to come back to understand more about the
casting but right now i just wanted to show you my
code. i hope it is readable and once again thanks for
your help in advance!
--- Fin Springs <[EMAIL PROTECTED]> wrote:
>
> On Feb 15, 2008, at 5:40 PM, C S usmsci-at-yahoo.com
> |sqlite| wrote:
>
> > hi all i have a question regarding Blobs, that is
> > storing images into the database.
> >
> > my image by default is an unsigned short array and
> to
> > bind blobs it wants a byte array. i am not sure i
> am
> > doing this right at all. is there a universal
> cross
> > platform way for this easy conversion?
> >
> > so far the code i have is:
> > .........
> > char *byteArray = (char *) malloc((size * 2) *
> > sizeof(char));
> > .........
> >
> > for(unsigned int i = 0; i < index < size; i++)
> > {
> > byteArray[2 * index] = (char)buffer[index];
> > byteArray[(2 * index) + 1] = ( (char)
> buffer[index]
> >>> 1);
> >
> There is probably no reason to copy your data into a
> separate char
> array. Presuming you have something like:
>
> unsigned short myImage[];
> size_t size; // the number of elements in your
> myImage array
>
> - you can just do:
>
> status = sqlite3_bind_blob(statement, 1, myImage,
> size *
> sizeof(unsigned short), SQLITE_STATIC or
> SQLITE_TRANSIENT)
>
> Your choice for the last parameter will depend on
> the life time of
> 'myImage'; see
> http://sqlite.org/c3ref/bind_blob.html
>
> > then i prepare the statement which is successful
> then:
> >
> > status = sqlite3_bind_blob(statement, 1,
> byteArray,
> > size * 2, free);
> >
> > some questions i have: i get an error of '25' back
> > from status and looking on the sqlite documention
> it
> > says the 2nd parameter to sql bind was out of
> range. i
> > have no idea how the 2nd parameter can be out of
> > range.
> You would need to share your statement definition.
> Is there at least
> one '?' token in it?
> >
> >
> > my next question is once you have the blob in the
> > database how in the world do you read it back out?
> of
> > course when i do read it back out i will need to
> > convert it back to a short array to be able to use
> it.
> >
> Use sqlite3_column_blob to get the pointer and
> sqlite3_column_bytes to
> know how much data there is (in bytes). You can just
> cast the 'const
> void *' pointer that you get back to a 'const
> unsigned short *' and
> divide the number of bytes there is by
> sizeof(unsigned short) (ie 2)
> to get the number of elements.
>
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>
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>
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