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Home » U++ Library support » U++ SQL » How to read a Blob from a SQLite3 DB (I can write a blob with a string but i can't read it )

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How to read a Blob from a SQLite3 DB [message #43970]

Tue, 02 December 2014 05:03

lmsp
Messages: 2
Registered: December 2014

Junior Member

I have the next code to write a BLOB in a SQLite3 DB:

My .sch file:

TABLE_(BLOBS_TABLE)
INT_ (NUMBER)
BLOB_ (DATA)
END_TABLE

And C++ write(I omit the code of creation an open the DB):

S_BLOBS_TABLE row;

row.NUMBER = 1;
row.DATA = String(blob.GetBuffer(), blob.GetBufferLength());

SQL * Insert(FILES_BLOBS_TABLE)(row);

The class blob.GetBuffer() returns a char* and blob.GetBufferLength() the size of the buffer in bytes.

My problem comes when I try to read the data. I have tried:

SQL.Execute("select DATA from BLOBS_TABLE WHERE NUMBER=" +AsString(1) );

if(SQL.Fetch())
{
StringBuffer data( SQL[0] );
char* pBuffer = new char[data.GetLength()];
memcpy( pBuffer, data, data.GetLength() );
}

And:

SQL.Execute("select DATA from BLOBS_TABLE WHERE NUMBER=" +AsString(1) );

if(SQL.Fetch())
{
String data = SQL[0];
char* pBuffer = new char[data.GetLength()];
memcpy( pBuffer, (const char*)data, data.GetLength() );
}

But any solution doesn't work. Any help?

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