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problem using perl to read small numbers from access database using microsoft access driver (*.mdb, *.accdb)

Posted on 2010-09-01
4
928 Views
Last Modified: 2012-08-13
Minimal version of problem attached. Numbers such as 1.23 are read ok using perl .mdb driver or .mdb, .accdb driver. Small numbers such as 1.23E-15 are read ok using .mdb driver, but not .accdb driver. Latter returns E-15 instead.

Have tried database in 2000,2003,2007 format and .accdb driver always has same behaviour. May be able to get away using older driver, but would like to understand how to make the newer one work.

I'm using active state perl 5.10

Output of code is shown below

Testing with driver microsoft access driver (*.mdb)
1 1.23
2 0.0000123
3 0.000000000123
4 1.23E-15
5 1.23E-20

Testing with driver microsoft access driver (*.mdb, *.accdb)
1 1.23
2 0.0000123
3 0.000000000123
4 E-15
5 E-20

#!/bin/perl
#
# Driver test on access table containing small numbers
#

use DBI;

$database = 'F:\temp\numericTest.mdb';


runTest('microsoft access driver (*.mdb)');
runTest('microsoft access driver (*.mdb, *.accdb)');


sub runTest {

      my $driver = shift(@_);
      print STDOUT "\nTesting with driver $driver\n";

     # Open database connection
     $dbh =  DBI->connect(
	'dbi:ODBC:driver='.$driver.';dbq=' . $database )
  || die "Can't connect to Kromer Database: $DBI::errstr";
      
     # run query
 	$sqlstatement =
	    "SELECT numbers from numbersTable";
	$sth = runQuery($sqlstatement);
	$cnt = 0;
	while ( @row = $sth->fetchrow_array() ) {
            $cnt++;
		$val = $row[0];
		print STDOUT "$cnt $val\n";
	}
     

     # print most recent errr if exists and close connection
     print $dbh->errstr;
     $dbh->disconnect;
}

sub runQuery {
	my $query = shift(@_);
	$sth = $dbh->prepare($sqlstatement)
	  || die "Can't prepare statement: $DBI::errstr";

	$sth->execute
	  || die "Could not execute SQL statement, check query";
	return $sth;
}

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numericTest.mdb
0
Comment
Question by:ian__hawkins
  • 2
4 Comments
 
LVL 6

Expert Comment

by:apresence
ID: 33575448
Shot in the dark, but can you try:
SELECT CDBl(numbers) AS numbers from numbersTable

This will convert the number to a double-precision type before returning, which should give you the accuracy you need without truncating data like what you're seeing.
0
 

Author Comment

by:ian__hawkins
ID: 33575594
Thanks for the suggestion. Unfortunately it did not change the result. (I have also tried printing out $sth->TYPE[0] after the select query, and both drivers return  8, corresponding to "double" as expected)
0
 
LVL 39

Accepted Solution

by:
Adam314 earned 500 total points
ID: 33605449
Don't know the cause of the error, but this work-around seems to work.
$sqlstatement = "SELECT FORMAT(numbers, 'Scientific') from numbersTable";

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0
 

Author Closing Comment

by:ian__hawkins
ID: 33609566
Many thanks for the reply - a good solution to the problem.
Ian
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