#include // for printf
#include // main SQLAPI++ header
// forwards
void IntoFileReader(
SAPieceType_t ePieceType,
void *pBuf,
size_t nLen,
size_t nBlobSize,
void *pAddlData);
int main(int argc, char* argv[])
{
SAConnection con; // connection object
SACommand cmd(
&con,
_TSA("Select fblob from test_tbl")); // command object
try
{
// connect to database (Oracle in our example)
con.Connect(_TSA("test"), _TSA("tester"), _TSA("tester"), SA_Oracle_Client);
// Usage 1. Read whole BLob(s) into internal buffers
// Select BLob from our test table
cmd.Execute();
// fetch results row by row and print results
while(cmd.FetchNext())
{
// after fetching a row all Long/Lob fields are automatically read into internal buffers
// just like other data types
SAString s = cmd.Field(_TSA("fblob")).asBLob();
printf("Size of BLob is %d bytes\n", s.GetLength());
}
// Usage 2. Read BLob in pieces providing user callback for BLob data processing
// Select blob from our test table
cmd.Execute();
// do not automatically read this field into internal buffer (into corresponding SAField object)
// we will provide a callback for BLob fetching after FetchNext
cmd.Field(_TSA("fblob")).setLongOrLobReaderMode(SA_LongOrLobReaderManual);
// fetch results row by row and print results
SAString sFilename;
int i = 0;
while(cmd.FetchNext())
{
sFilename.Format(_TSA("fblob%d.bin"), ++i);
// at that moment all fields are fetched except
// those that set for manual retrieving
// read them (fblob in our example) now
if(!cmd.Field(_TSA("fblob")).isNull())
cmd.Field(_TSA("fblob")).ReadLongOrLob(
IntoFileReader, // our callback to read BLob content into file
10*1024, // our desired piece size
(void*)sFilename.GetMultiByteChars() // additional data, filename in our example
);
}
// commit changes on success
con.Commit();
printf("Rows with BLob field fetched!\n");
}
catch(SAException &x)
{
// SAConnection::Rollback()
// can also throw an exception
// (if a network error for example),
// we will be ready
try
{
// on error rollback changes
con.Rollback();
}
catch(SAException &)
{
}
// print error message
printf("%s\n", x.ErrText().GetMultiByteChars());
}
return 0;
}
static FILE *pFile = NULL;
size_t nTotalRead;
void IntoFileReader(
SAPieceType_t ePieceType,
void *pBuf,
size_t nLen,
size_t nBlobSize,
void *pAddlData)
{
if(ePieceType == SA_FirstPiece || ePieceType == SA_OnePiece)
{
nTotalRead = 0;
const char *sFilename = (const char *)pAddlData;
pFile = fopen(sFilename, "wb");
if (!pFile)
{
SAString sName(sFilename);
SAException::throwUserException(-1, _TSA("Can not open file '%s' for writing"), sName);
}
}
fwrite(pBuf, 1, nLen, pFile);
nTotalRead += nLen;
// show progress
printf("%d bytes of %d read\n", nTotalRead, nBlobSize);
if(ePieceType == SA_LastPiece || ePieceType == SA_OnePiece)
{
fclose(pFile);
pFile = NULL;
}
}