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On 08/17/2011 09:25 PM, Ivan Shmakov wrote:
> Somehow, I've assumed that sqlite3_bind_blob () will bind a
> parameter to a blob.
It does. There are no affinity rules that will cause otherwise.
There are some operations that cause blobs to be silently promoted to
strings. IMHO these are egregious errors in SQLite since a bucket of
bytes cannot be turned into characters unless you know the encoding
which SQLite doesn't. Here is an example:
sqlite> select X'616263' || 'd';
abcd
sqlite> select typeof(X'616263' || 'd');
text
Consequently if you had a trigger pulling a stunt like this, your code
could try to insert a blob and silently (wrongly) end up with a string.
SQLite won't even complain if the blob isn't a valid text encoding
producing an invalid string.
sqlite> select X'8989' || 'd';
��d
sqlite> select typeof(X'8989' || 'd');
text
sqlite> select hex(X'8989' || 'd');
898964
sqlite> create table x(y);
sqlite> INSERT INTO x values(X'8989' || 'd');
sqlite> .dump
PRAGMA foreign_keys=OFF;
BEGIN TRANSACTION;
CREATE TABLE x(y);
INSERT INTO "x" VALUES('��d');
COMMIT;
Roger
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