Beefy Boxes and Bandwidth Generously Provided by pair Networks
Perl-Sensitive Sunglasses
 
PerlMonks  

Re^2: Database processing

by DrAxeman (Beadle)
on Aug 06, 2005 at 02:14 UTC ( #481423=note: print w/ replies, xml ) Need Help??


in reply to Re: Database processing
in thread DBI::st=HASH output

I'm getting an error that I can't figure out:

SQL ERROR: Bad set function before FROM clause. Execution ERROR: No command found!. $VAR1 = undef;
Here's the code, just to make sure I'm using it right.
#!/usr/bin/perl use strict; use warnings; use DBI; #use Text::CSV; use Data::Dumper; # Connect to the database, (the directory containing our csv file( +s)) my $dbh = DBI->connect("DBI:CSV:f_dir=.;csv_eol=\n;"); # Associate our csv file with the table name 'results' $dbh->{'csv_tables'}->{'results'} = { 'file' => 'test.csv'}; my $sth = $dbh->prepare("SELECT * FROM results WHERE 1=0"); $sth->execute; my @cols = @{$sth->{NAME}}; my $avgSQL = 'SELECT ' . join(', ', map { "avg($_) as $_" } @cols ) . ' FROM results'; my $avgsHashRef = $dbh->selectrow_hashref($avgSQL); print Dumper $avgsHashRef;


Comment on Re^2: Database processing
Select or Download Code
Re^3: Database processing
by davidrw (Prior) on Aug 06, 2005 at 02:37 UTC
    hmm... print out $avgSQL and make sure it's valid sql. If there's anything funky (/\W/) in the column names they'll need to be escaped.
      I printed $avgSQL and got:
      SELECT avg(PDH_CSV40_EasternDaylightTime_240_) as PDH_CSV40_EasternDay +lightTime_240_, avg(ERWWCOMMUNITIES_Memory_Pages_sec) as ERWWCOMMUNIT +IES_Memory_Pages_sec, avg(ERWWCOMMUNITIES_NetworkInterface_CompaqEthe +rnet_FastEthernetAdapter_Module_BytesTotalPERsec) as ERWWCOMMUNITIES_ +NetworkInterface_CompaqEthernet_FastEthernetAdapter_Module_BytesTotal +PERsec, avg(ERWWCOMMUNITIES_NetworkInterface_MSTCPLoopbackinterface_B +ytesTotalPERsec) as ERWWCOMMUNITIES_NetworkInterface_MSTCPLoopbackint +erface_BytesTotalPERsec, avg(ERWWCOMMUNITIES_NetworkInterface_CompaqE +thernet_FastEthernetAdapter_Module_CurrentBandwidth) as ERWWCOMMUNITI +ES_NetworkInterface_CompaqEthernet_FastEthernetAdapter_Module_Current +Bandwidth, avg(ERWWCOMMUNITIES_NetworkInterface_MSTCPLoopbackinterfac +e_CurrentBandwidth) as ERWWCOMMUNITIES_NetworkInterface_MSTCPLoopback +interface_CurrentBandwidth, avg(ERWWCOMMUNITIES_PhysicalDisk_0C_PCTDi +skTime) as ERWWCOMMUNITIES_PhysicalDisk_0C_PCTDiskTime, avg(ERWWCOMMU +NITIES_PhysicalDisk_1D_PCTDiskTime) as ERWWCOMMUNITIES_PhysicalDisk_1 +D_PCTDiskTime, avg(ERWWCOMMUNITIES_PhysicalDisk_Total_PCTDiskTime) as + ERWWCOMMUNITIES_PhysicalDisk_Total_PCTDiskTime, avg(ERWWCOMMUNITIES_ +PhysicalDisk_Total_AvgDiskQueueLength) as ERWWCOMMUNITIES_PhysicalDis +k_Total_AvgDiskQueueLength, avg(ERWWCOMMUNITIES_Processor_Total_PCTPr +ocessorTime) as ERWWCOMMUNITIES_Processor_Total_PCTProcessorTime, avg +(ERWWDC1_Memory_PagesPERsec) as ERWWDC1_Memory_PagesPERsec, avg(ERWWD +C1_NetworkInterface_IntelPRO_100NetworkConnection_BytesTotalPERsec) a +s ERWWDC1_NetworkInterface_IntelPRO_100NetworkConnection_BytesTotalPE +Rsec, avg(ERWWDC1_NetworkInterface_MSTCPLoopbackinterface_BytesTotalP +ERsec) as ERWWDC1_NetworkInterface_MSTCPLoopbackinterface_BytesTotalP +ERsec, avg(ERWWDC1_NetworkInterface_IntelPRO_100NetworkConnection_Cur +rentBandwidth) as ERWWDC1_NetworkInterface_IntelPRO_100NetworkConnect +ion_CurrentBandwidth, avg(ERWWDC1_NetworkInterface_MSTCPLoopbackinter +face_CurrentBandwidth) as ERWWDC1_NetworkInterface_MSTCPLoopbackinter +face_CurrentBandwidth, avg(ERWWDC1_PhysicalDisk_0C_PCTDiskTime) as ER +WWDC1_PhysicalDisk_0C_PCTDiskTime, avg(ERWWDC1_PhysicalDisk_Total_PCT +DiskTime) as ERWWDC1_PhysicalDisk_Total_PCTDiskTime, avg(ERWWDC1_Phys +icalDisk_Total_AvgDiskQueueLength) as ERWWDC1_PhysicalDisk_Total_AvgD +iskQueueLength, avg(ERWWDC1_Processor_Total_PCTProcessorTime) as ERWW +DC1_Processor_Total_PCTProcessorTime, avg(ERWWNAB_Memory_PagesPERsec) + as ERWWNAB_Memory_PagesPERsec, avg(ERWWNAB_NetworkInterface_Intel825 +5x_basedIntegratedFastEthernet_BytesTotalPERsec) as ERWWNAB_NetworkIn +terface_Intel8255x_basedIntegratedFastEthernet_BytesTotalPERsec, avg( +ERWWNAB_NetworkInterface_MSTCPLoopbackinterface_BytesTotalPERsec) as +ERWWNAB_NetworkInterface_MSTCPLoopbackinterface_BytesTotalPERsec, avg +(ERWWNAB_NetworkInterface_Intel8255x_basedIntegratedFastEthernet_Curr +entBandwidth) as ERWWNAB_NetworkInterface_Intel8255x_basedIntegratedF +astEthernet_CurrentBandwidth, avg(ERWWNAB_NetworkInterface_MSTCPLoopb +ackinterface_CurrentBandwidth) as ERWWNAB_NetworkInterface_MSTCPLoopb +ackinterface_CurrentBandwidth, avg(ERWWNAB_PhysicalDisk_0C_PCTDiskTim +e) as ERWWNAB_PhysicalDisk_0C_PCTDiskTime, avg(ERWWNAB_PhysicalDisk_T +otal_PCTDiskTime) as ERWWNAB_PhysicalDisk_Total_PCTDiskTime, avg(ERWW +NAB_PhysicalDisk_Total_AvgDiskQueueLength) as ERWWNAB_PhysicalDisk_To +tal_AvgDiskQueueLength, avg(ERWWNAB_Processor_Total_PCTProcessorTime) + as ERWWNAB_Processor_Total_PCTProcessorTime, avg(ERWWSEARCH_Memory_P +agesPERsec) as ERWWSEARCH_Memory_PagesPERsec, avg(ERWWSEARCH_NetworkI +nterface_BroadcomNetXtremeGigabitEthernetDriver_BytesTotalPERsec) as +ERWWSEARCH_NetworkInterface_BroadcomNetXtremeGigabitEthernetDriver_By +tesTotalPERsec, avg(ERWWSEARCH_NetworkInterface_IntelPRO_100NetworkCo +nnection_BytesTotalPERsec) as ERWWSEARCH_NetworkInterface_IntelPRO_10 +0NetworkConnection_BytesTotalPERsec, avg(ERWWSEARCH_NetworkInterface_ +MSTCPLoopbackinterface_BytesTotalPERsec) as ERWWSEARCH_NetworkInterfa +ce_MSTCPLoopbackinterface_BytesTotalPERsec, avg(ERWWSEARCH_NetworkInt +erface_BroadcomNetXtremeGigabitEthernetDriver_CurrentBandwidth) as ER +WWSEARCH_NetworkInterface_BroadcomNetXtremeGigabitEthernetDriver_Curr +entBandwidth, avg(ERWWSEARCH_NetworkInterface_IntelPRO_100NetworkConn +ection_CurrentBandwidth) as ERWWSEARCH_NetworkInterface_IntelPRO_100N +etworkConnection_CurrentBandwidth, avg(ERWWSEARCH_NetworkInterface_MS +TCPLoopbackinterface_CurrentBandwidth) as ERWWSEARCH_NetworkInterface +_MSTCPLoopbackinterface_CurrentBandwidth, avg(ERWWSEARCH_PhysicalDisk +_0CD_PCTDiskTime) as ERWWSEARCH_PhysicalDisk_0CD_PCTDiskTime, avg(ERW +WSEARCH_PhysicalDisk_Total_PCTDiskTime) as ERWWSEARCH_PhysicalDisk_To +tal_PCTDiskTime, avg(ERWWSEARCH_PhysicalDisk_Total_AvgDiskQueueLength +) as ERWWSEARCH_PhysicalDisk_Total_AvgDiskQueueLength, avg(ERWWSEARCH +_Processor_Total_PCTProcessorTime) as ERWWSEARCH_Processor_Total_PCTP +rocessorTime, avg(ERWWSQLWEB_Memory_PagesPERsec) as ERWWSQLWEB_Memory +_PagesPERsec, avg(ERWWSQLWEB_NetworkInterface_BroadcomNetXtremeGigabi +tEthernetDriver_BytesTotalPERsec) as ERWWSQLWEB_NetworkInterface_Broa +dcomNetXtremeGigabitEthernetDriver_BytesTotalPERsec, avg(ERWWSQLWEB_N +etworkInterface_MSTCPLoopbackinterface_BytesTotalPERsec) as ERWWSQLWE +B_NetworkInterface_MSTCPLoopbackinterface_BytesTotalPERsec, avg(ERWWS +QLWEB_NetworkInterface_BroadcomNetXtremeGigabitEthernetDriver_Current +Bandwidth) as ERWWSQLWEB_NetworkInterface_BroadcomNetXtremeGigabitEth +ernetDriver_CurrentBandwidth, avg(ERWWSQLWEB_NetworkInterface_MSTCPLo +opbackinterface_CurrentBandwidth) as ERWWSQLWEB_NetworkInterface_MSTC +PLoopbackinterface_CurrentBandwidth, avg(ERWWSQLWEB_PhysicalDisk_0CD_ +PCTDiskTime) as ERWWSQLWEB_PhysicalDisk_0CD_PCTDiskTime, avg(ERWWSQLW +EB_PhysicalDisk_Total_PCTDiskTime) as ERWWSQLWEB_PhysicalDisk_Total_P +CTDiskTime, avg(ERWWSQLWEB_PhysicalDisk_Total_AvgDiskQueueLength) as +ERWWSQLWEB_PhysicalDisk_Total_AvgDiskQueueLength, avg(ERWWSQLWEB_Proc +essor_Total_PCTProcessorTime) as ERWWSQLWEB_Processor_Total_PCTProces +sorTime FROM results
      It looks OK to me, but then again, I'm a novice at SQL.
      I do a lot of preprocessing to the csv files before I run them through the perl script. I remove spaces, , , (, ), etc... the list above has all column names in it. I'm wondering if this should be looped? These csv files will average about 30 columns and upto 6000 rows. Doing all the average calculations in one command may be a little taxing on my system.

      PS. I don't need the data after the average is calculated. Just the column name and the average. Also, I don't need the first column, that can just go away.
        You can tweak the map to be map { "avg($_) as $_\n" } to make it a little more legible, and then browse for errors. Did you try running the SQL directly in your db? What about a portion (e.g. w/just a few columns) of it?

        If you want to exclude columns, simply grep them out of @cols, or to just ditch the first one, do a shift @cols;
        Doing all the average calculations in one command may be a little taxing on my system.
        No, doing all the average calculations in many commands is what will tax your system. If you do it in separate statements, you're making the database go through all 6000 rows 30 different times. But if you do it in one statement, it only needs one pass.
Re^3: Database processing
by jZed (Prior) on Aug 06, 2005 at 05:38 UTC
    Your script works for me (maintainer of DBD::CSV and SQL::Statement) with a smaller dataset. Could you let me know which version of SQL::Statement you have? If you have anything ealier than 1.14, you should probably upgrade.

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://481423]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others chanting in the Monastery: (8)
As of 2014-12-21 05:13 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    Is guessing a good strategy for surviving in the IT business?





    Results (103 votes), past polls