For completeness, please note that this is a limitation of DBD::mysql, not of MySQL. From the MySQL documentation: 

ROW_COUNT() returns the number of rows changed, deleted, or inserted b
+y the last statement if it was an UPDATE, DELETE, or INSERT.

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For UPDATE statements, the affected-rows value by default is the numbe
+r of rows actually changed. If you specify the CLIENT_FOUND_ROWS flag
+ to mysql_real_connect() when connecting to mysqld, the affected-rows
+ value is the number of rows “found”; that is, matched by the WHERE c
+lause.

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Unfortunately it also says below: 
Important
ROW_COUNT() is not replicated reliably.

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Which I take it is the reason why it doesn't even work to call that function directly (through DBI) as in: 
my $rows = $dbh->selectrow_array( 'select row_count()' );

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. . . which still returns the number of "found" rows (those that match the where clause), not the number of changed rows, as do $sth->rows and the return value of $dbh->do. This is very odd, in my view, since when I run that same SQL in the MySQL CLI, it does return the number of changed rows.

The way forward always starts with a minimal test.

In reply to Re: [Solved]: How to get count of rows changed by MySQL UPDATE command using DBI by 1nickt
in thread [Solved]: How to get count of rows changed by MySQL UPDATE command using DBI by Perl300

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