$sth->rows, doesn't return the correct number of rows return

$sth->rows, doesn't return the correct number of rows return

Post by rakuma » Sat, 07 May 2005 00:48:31

Hi Guys,

When i do select quiery and then try to get count of rows like this in perl
script from Oracle database and Informix:

$rowCnt = $sth->rows;

above line is being executed after the $sth->execute;

This problem I am facing in Informix and Oracle both.

Any suggestions or solution would be great help.


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$sth->rows, doesn't return the correct number of rows return

Post by keit » Sat, 07 May 2005 04:48:29

But before you've fetched the rows, presumably. Have you read
the DBI documentation on ->rows()?

http://www.yqcomputer.com/ ~timb/DBI-1.48/DBI.pm#rows

Keith Ivey < XXXX@XXXXX.COM >
Smokefree DC
Washington, DC


$sth->rows, doesn't return the correct number of rows return

Post by llose » Sat, 07 May 2005 04:56:15

You are not very specific with respect to when you are trying to get
the count of rows. However, from the doc, for SELECT queries the
returned value is only valid after all rows have been retrieved.:

$rv = $sth->rows;
Returns the number of rows affected by the last row affecting command,
or -1 if the number of rows is not known or not available.

Generally, you can only rely on a row count after a non-SELECT execute
(for some specific operations like UPDATE and DELETE), or after
fetching all the rows of a SELECT statement.

For SELECT statements, it is generally not possible to know how many
rows will be returned except by fetching them all. Some drivers will
return the number of rows the application has fetched so far, but
others may return -1 until all rows have been fetched. So use of the
rows method or $DBI::rows with SELECT statements is not recommended.

One alternative method to get a row count for a SELECT is to execute a
``SELECT COUNT(*) FROM ...'' SQL statement with the same ``...'' as
your query and then fetch the row count from that.