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return number of rows selected

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# 1  
Old 04-05-2006
return number of rows to PERL selected in SQL
Hi all, i am doing a perl script to read from a db. I am able to retrieve the rows, but i am unable to return the number of rows selected. i tried
Code:
$selectedrows = $sth->numrows;

i got the error msg:
Can't locate object method "numrows" via package "DBI::st"
i changed it to
Code:
 $selectedrows = $sth->rows;

i get 0, when i have results returned.

Any advise, thanks.
Last edited by new2ss; 04-05-2006 at 05:22 AM..
# 2  
Old 04-05-2006
Which database driver did you use (the one indicated in the connection string)?
# 3  
Old 01-08-2007
Hi Cbkihong!

I am also facing the same error. Can you please provide the information about what is the difference between $sth->numrows and $sth->rows.
Also I want to know if there is some restriction on the use of $sth->rows as I am also getting 0 even when there are rows in the database.

Kindly guide.

regards
Apoorva Kumar
# 4  
Old 01-08-2007
The easiest way to find out how many rows a query will return is to use the COUNT function in SQL.

For operations that aren't queries (such as INSERTs, UPDATEs, and DELETEs), the do method returns the number of rows affected, -1 when it can't determine the right value, or else undef in case of failure.

Code:
$rows = $dbh->do("DELETE FROM Conference WHERE Language='REBOL'");
if (! defined $rows) {
  # failed, but this is not needed if RaiseError is active
} else {
  print "Deleted $rows rows\n";
}

# 5  
Old 01-08-2007
Dear Anbu!
Thanks for the quick reply. The statment I am using is a Select one. can I use the do method on select statement also?

regards
Apoorva Kumar
# 6  
Old 01-08-2007
do is used to retrieve row counts for other than select.

For example if
Code:
SELECT id,name FROM People WHERE Age > 30

is the query you use then use count to get row count

Code:
SELECT COUNT(*) FROM People WHERE Age > 30

# 7  
Old 01-08-2007
Quote:
Originally Posted by apoorvasharma80
Dear Anbu!
Thanks for the quick reply. The statment I am using is a Select one. can I use the do method on select statement also?
No. This is because no resultset is prepared with the do() method. Please refer to the manual page for DBI (http://search.cpan.org/~timb/DBI-1.53/DBI.pm#do)

Quote:
Prepare and execute a single statement. Returns the number of rows affected or undef on error. A return value of -1 means the number of rows is not known, not applicable, or not available.

This method is typically most useful for non-SELECT statements that either cannot be prepared in advance (due to a limitation of the driver) or do not need to be executed repeatedly. It should not be used for SELECT statements because it does not return a statement handle (so you can't fetch any data).
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