Read Data From A BLOB Incrementally

int sqlite3_blob_read(sqlite3_blob *, void *Z, int N, int iOffset);

This function is used to read data from an open BLOB handle into a caller-supplied buffer- N bytes of data are copied into buffer Z from the open BLOB, starting at offset iOffset-

If offset iOffset is less than N bytes from the end of the BLOB, SQLITE_ERROR is returned and no data is read. If N or iOffset is less than zero, SQLITE_ERROR is returned and no data is read. The size of the blob (and hence the maximum value of N+iOffset) can be determined using the sqlite3_blob_bytes() interface.

An attempt to read from an expired BLOB handle fails with an error code of 登录查看完整内容