On 24/06/11 16:17, David Nicol wrote:
On Sat, Jun 11, 2011 at 12:51 PM, Tim Bunce<tim.bu...@pobox.com> wrote:
Patch welcome.
Tim.
here's a revised new paragraph, to go right before the =head3 C<prepare>.
BEGIN THING TO INSERT
=head3 On use of non-C<SELECT> SQL in C<select*_*> methods
While some drivers support statements other than C<SELECT> in the above-listed
convenience functions, others do not: driver support for this facility
is not defined
by the DBI interface standard, and the C<do> method is provided for
non-C<SELECT>
statements. When you really don't know if the statement you have in a
variable is going
to be a C<SELECT> or not, unrolling the process into C<prepare>,C<execute>,
and
a C<fetch*> called within an C<eval> block will work.
END THING TO INSERT
Unfortunately this does not hold true for DBD::ODBC:
perl -le 'use DBI; my $h = DBI->connect(); my $s = $h->prepare("create table fred (a
int)"); $s->execute; my $r = $s->fetch;'
DBD::ODBC::st fetch failed: no select statement currently executing (SQL-HY000)
at -e line 1.
Does this mean DBD::ODBC has a bug?
If so, and as I said before, I don't think DBD::ODBC knows the difference
between a fetch called as part of selectall_* or a fetch called directly and
the only way out would be to report no errors in fetch at all if the statement
is not active.
AV *dbd_st_fetch(SV *sth, imp_sth_t *imp_sth)
{
D_imp_dbh_from_sth;
D_imp_xxh(sth);
int i;
AV *av;
RETCODE rc;
int num_fields;
#ifdef TIMESTAMP_STRUCT /* iODBC doesn't define this */
char cvbuf[512];
#endif
int ChopBlanks;
/* Check that execute() was executed sucessfully. This also implies */
/* that dbd_describe() executed sucessfuly so the memory buffers */
/* are allocated and bound. */
if ( !DBIc_ACTIVE(imp_sth) ) {
dbd_error(sth, DBDODBC_INTERNAL_ERROR, "no select statement currently
executing");
return Nullav;
}
the alternate of calling the select_*_ in the eval, then falling back
to the do, is not suggested,
as it might cause the SQL to get done twice. I think explicitly warning against
my $ar;
eval { $ar = $dbh-> selectall_arrayref($SQL); 1} or $dbh->do{$SQL);
would be going too far.
Martin
--
Martin J. Evans
Easysoft Limited
http://www.easysoft.com
