Question

数据表有太多列可以逐个选择，所以我试图将整个数据拉入文件。有许多列包含UTC和当地时间的日期时间。当我使用以下脚本时，将删除所有小时信息，并仅保存日期。如何轻松修复代码以保存整个日期时间信息？

总之，csv文件中的所有日期时间数据都保存为＆＃34; 25-FEB-15＆＃34;而不是＆＃34; 25-FEB-15 HH：MM：SS AM -08：00＆＃34;

open(OUTFILE, "> ./outputfile.csv");  

my($dbh,$sth);
$dbh = DBI->connect("xxx")

my $sqlGetEid = "

select *
from Table_1
where MARKET = 'Chicago' and DATETIMELOCAL >= '22-FEB-2015' and DATETIMELOCAL < '01-MAR-2015' 

";

my $curSqlEid = $dbh->prepare($sqlGetEid);

$curSqlEid->execute();

my $counter = 0;
my $delimiter = ',';
my $fields = join(',', @{ $curSqlEid->{NAME_lc} });
print "$fields\n";
printf OUTFILE "$fields\n";

while (my @row = $curSqlEid->fetchrow_array) {  
    my $csv = join(',', @row)."\n";
    printf OUTFILE "$csv";
    $counter ++;
    if($counter % 10000 == 0){
        print $csv, "\n";
    }
}

根据以下评论我有固定代码，但问题尚未解决。我使用的数据库是Oracle，因此基于MySQL的代码似乎不兼容。问题缩小到Oracle使用的日期时间格式，因此通过正确处理格式可以解决此问题。但我不确定我必须使用哪个perl包来很好地处理Oracle数据时间格式。

use DBI;
use DBD::Oracle qw(:ora_types);
use Compress::Zlib;
use FileHandle;
use strict;
use warnings;
use DateTime;
use Data::Dumper;
use Text::CSV_XS;
use DateTime::Format::DateParse;
use DateTime::Format::DBI;


open(OUTFILE, "> ./output.csv");  

my $dbh = DBI->connect("xxx")

my $sth = $dbh->prepare("SELECT * FROM Table_1");
$sth->execute;
my $fields = join(',', @{ $sth->{NAME_lc} });


#EXTRACT COLUMN NAMES
my @col_names = @{ $sth->{NAME_lc} } ;
my $column_names = join ", ", @col_names;


my $select = "
select $column_names
from Table_1
where MARKET = 'Chicago' and DATETIMELOCAL >= '22-FEB-2015' and DATETIMELOCAL < '01-MAR-2015' 
";

my $query = $dbh->prepare($select);
$query->execute;

#WRITE DATA TO CSV FILE
my $csv_attributes = {
    binary => 1,  #recommneded
    eol => $/,    #recommended(I wonder why it's not $\ ?)
};

my $csv = Text::CSV_XS->new($csv_attributes);

my $fname = 'data.csv';
open my $OUTFILE, ">", $fname
    or die "Couldn't open $fname: $!";
$csv->print($OUTFILE, \@col_names);
$csv->column_names(@col_names);  #Needed for print_hr() below

while (my $row = $query->fetchrow_arrayref) {

    print  $row->[0];# $row->{datetimelocal} does not work
    my $datetime = DateTime::Format::DBI->parse_datetime( $row->[0]) ; # This might be wrong

    $row->[0] = strftime("%d-%b-%y %I:%M:%S %p", $datetime);    
    $csv->print($OUTFILE, $row);
}


close $OUTFILE;

$query->finish;
$dbh->disconnect;

Answer 1

数据表有太多列无法逐一选择

不是问题。毕竟我们是计算机程序员。

总之，csv文件中的所有日期时间数据都保存为＆＃34; 25-FEB-15＆＃34; 而不是＆＃34; 25-FEB-15 HH：MM：SS AM -08：00＆＃34;

我没有看到：

use strict; 
use warnings; 
use 5.012;
use Data::Dumper;

use DBI;
use DBD::mysql;
use Text::CSV_XS;

#CONFIG VARIABLES
my $db_type = "mysql";
my $database = "my_db";
my $host = "localhost";
my $port = "3306";
my $user = "root";
my $pword = "";

#DATA SOURCE NAME
my $dsn = "dbi:$db_type:$database:$host:$port";

#PERL DBI CONNECT
my $dbh = DBI->connect($dsn, $user, $pword);

my $tablename = "Table_1";

#CONDITIONALLY DROP THE TABLE
my $drop_table = "drop table if exists $tablename;";
my $query = $dbh->prepare($drop_table);
$query->execute();

#CONDITIONALLY CREATE THE TABLE
my $create_table =<<"END_OF_CREATE"; 
create table $tablename (
    id INT(12) not null auto_increment primary key, 
    open DECIMAL(6,4),
    high DECIMAL(6,4),
    low DECIMAL(6,4),
    close DECIMAL(6,4),
    market VARCHAR(40),
    datetimelocal DATETIME
)
END_OF_CREATE

$query = $dbh->prepare($create_table);
$query->execute();

#INSERT DATA INTO TABLE
my $insert =<<"END_OF_INSERT";
    insert into $tablename(open, high, low, close, market, datetimelocal)
    values (?, ?, ?, ?, ?, ?)
END_OF_INSERT

my @data = (
    [10.00, 12.00, 9.00, 11.50, 'Chicago', '2015-2-23 16:00:01'],
    [10.00, 12.01, 9.01, 11.51, 'New York', '2015-2-23 16:00:01'],
);

for my $aref (@data) {
    $query = $dbh->prepare($insert);
    $query->execute(@$aref);
}

#PREPARE COLUMN NAME QUERY
my $select =<<"END_OF_SELECT";
    SELECT column_name
    FROM information_schema.columns
    WHERE table_name='Table_1'; 
END_OF_SELECT

$query = $dbh->prepare($select);
$query->execute;

#EXTRACT COLUMN NAMES
my @col_names = @{$dbh->selectcol_arrayref($query)};
my $column_names = join ", ", @col_names;

#PREPARE SELECT QUERY
$select =<<"END_OF_SELECT";
    select $column_names from $tablename
    where MARKET = 'Chicago' and DATETIMELOCAL >= '2015-2-22' and DATETIMELOCAL < '2015-3-1' 
END_OF_SELECT

$query = $dbh->prepare($select);
$query->execute;

#WRITE DATA TO CSV FILE
my $csv_attributes = {
    binary => 1,  #recommneded
    eol => $/,    #recommended(I wonder why it's not $\ ?)
};

my $csv = Text::CSV_XS->new($csv_attributes);

my $fname = 'data.csv';
open my $OUTFILE, ">", $fname
    or die "Couldn't open $fname: $!";
$csv->print($OUTFILE, \@col_names);

while (my $row = $query->fetchrow_arrayref) {
    $csv->print($OUTFILE, $row);
}

close $OUTFILE;

$query->finish;
$dbh->disconnect;

db table：

mysql> describe Table_1;
+---------------+--------------+------+-----+---------+----------------+
| Field         | Type         | Null | Key | Default | Extra          |
+---------------+--------------+------+-----+---------+----------------+
| id            | int(12)      | NO   | PRI | NULL    | auto_increment |
| open          | decimal(6,4) | YES  |     | NULL    |                |
| high          | decimal(6,4) | YES  |     | NULL    |                |
| low           | decimal(6,4) | YES  |     | NULL    |                |
| close         | decimal(6,4) | YES  |     | NULL    |                |
| market        | varchar(40)  | YES  |     | NULL    |                |
| datetimelocal | datetime     | YES  |     | NULL    |                |
+---------------+--------------+------+-----+---------+----------------+
7 rows in set (0.19 sec)

mysql> select * from Table_1;
+----+---------+---------+--------+---------+----------+---------------------+
| id | open    | high    | low    | close   | market   | datetimelocal       |
+----+---------+---------+--------+---------+----------+---------------------+
|  1 | 10.0000 | 12.0000 | 9.0000 | 11.5000 | Chicago  | 2015-02-23 16:00:01 |
|  2 | 10.0000 | 12.0100 | 9.0100 | 11.5100 | New York | 2015-02-23 16:00:01 |
+----+---------+---------+--------+---------+----------+---------------------+
2 rows in set (0.00 sec)

输出：

$ cat data.csv
id,open,high,low,close,market,datetimelocal
1,10.0000,12.0000,9.0000,11.5000,Chicago,"2015-02-23 16:00:01"

csv文件中的所有日期时间数据都保存为＆＃34; 25-FEB-15＆＃34;代替＆＃34; 25-FEB-15 HH：MM：SS AM -08：00＆＃34;

请注意，mysql DATETIME列类型不会保存时区偏移量信息。如果要格式化日期时间并添加时区偏移量，可以执行以下操作：

...
...
use DateTime::Format::MySQL;
use DateTime::Format::Strptime qw{ strftime };

...
...

#WRITE DATA TO CSV FILE
my $csv_attributes = {
    binary => 1,  #recommneded
    eol => $/,    #recommended(I wonder why it's not $\ ?)
};

my $csv = Text::CSV_XS->new($csv_attributes);

my $fname = 'data.csv';
open my $OUTFILE, ">", $fname
    or die "Couldn't open $fname: $!";

$csv->print($OUTFILE, \@col_names);
$csv->column_names(@col_names);  #Needed for print_hr() below

my $tz_offset = "-08:00";

while (my $row = $query->fetchrow_hashref) {
    my $datetime = DateTime::Format::MySQL->parse_datetime(
        $row->{datetimelocal}
    ); 

    #strftime() comes from DateTime::Format::Strptime:
    $row->{datetimelocal} = strftime(
        "%d-%b-%y %I:%M:%S %p $tz_offset", 
        $datetime
    );

    $csv->print_hr($OUTFILE, $row); #=>print hash ref.  To get the column order right, you first have to set the column order with $csv->column_names().
}

close $OUTFILE;

$query->finish;
$dbh->disconnect;

输出：

$ cat data.csv
id,open,high,low,close,market,datetimelocal
1,10.0000,12.0000,9.0000,11.5000,Chicago,"23-Feb-15 04:00:01 PM -08:00"

Answer 2

明确选择每列。对于日期列，选择具有所需格式的列的TO_DATE

Perl，SQL查询并使用正确的日期时间格式将数据保存到csv文件

2 个答案: