Hope you guys will be able to help me out on this one, still new to Perl and working it out as a go !?! I'm reading a CSV File and storing the fields into variables. The CSV data can contain empty fields. These are being treated by Perl as undefined variables - which is what I believe is Perl's interpretation of NULL. I want to be able to write these undefined variables to my table (using DBI) which will then be stored as NULL values on my table. The code below is the segment updating the Database... whole script is 600 lines long so best not to post it all! 
                # INSERT RECORD INTO MET_OFFICE_RAW_DATA TABLE

                no warnings 'uninitialized';
                my $mo_raw_sql = "REPLACE INTO met_office_raw_data
                             SET observation_datetime_utc   = '$file_o
+bs_datetime_utc',
                             observation_datetime_local = '$file_obs_d
+atetime_local',
                             observation_datetime        = '$file_obs_
+datetime',
                             station_id                 = '$file_stati
+on_id',
                             station_name            = '$file_station_
+name',
                             temp_c                = '$file_temp_c',
                             dewpoint_c            = '$file_dewpoint_c
+',
                             humidity_rh            = '$file_humidity_
+rh',
                             wind_dir_compass        = '$file_wind_dir
+_compass',
                             wind_speed_mph            = '$file_wind_s
+peed_mph',
                             wind_gust_mph            = '$file_wind_gu
+st_mph',
                             visibility_metres        = '$file_visibil
+ity_metres',
                             pressure_hpa            = '$file_pressure
+_hpa',
                             pressure_tendency        = '$file_pressur
+e_tendency',
                             weather_type            = '$file_weather_
+type'";

                my $mo_raw = $dbh->do($mo_raw_sql, undef)
                    or die "Could not Insert record into met_office_ra
+w_data \n";

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The fields that are undefined are being written as 0.00, 0 or " " not NULL. I found an unclear reference where I thought the ..., undef) parameter on the $dbh->do would map the undef variables to NULL in MySQL but this appears to make no difference. I've read bits on data binding for this but not sure how I can apply it to my code. Hopefully I'm missing something simple - very grateful for any assistance - Thanks

In reply to Writing NULL values to a MySQL record via DBI by ureco

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