user @ host：〜＃ mysql -V-mysql版本14.14发行版5.7.25-28，用于debian-linux-gnu（x86_64），使用在debian-9,9下运行的7.0
user @ host：〜＃ uname -a-Linux 4.9.0-8-amd64＃1 SMP Debian 4.9.144-3.1（2019-02-19）x86_64 GNU / Linux
user @ host：〜＃ perl -MDBI -e 'print $DBI::VERSION ."\n";'-1.636
user @ host：〜＃ perl -v这是为x86_64-linux-gnu-thread-multi构建的perl 5，版本24，版本1（v5.24.1）
mysql> SHOW CREATE TABLE tbl1;
tbl1 |创建表`tbl1`（`id` bigint（20）NOT NULL AUTO_INCREMENT，main_id bigint（20）NOT NULL DEFAULT'0'，`debet` varchar（255）NOT NULL DEFAULT``，`kurs` double（20,4）NOT NULL默认'0.0000'，sum sum double（20,2）NOT NULL默认值'0.00'，is_sync` int（11）NOT NULL默认为'0'，主键（`id`），KEY`main_id`（`main_id`））ENGINE = InnoDB AUTO_INCREMENT = 70013000018275 DEFAULT CHARSET = utf8
mysql> SELECT * FROM tbl1 WHERE id=70003020040132;
-+ --------------- + ---------------- + ------- + ------- -+ --------- + --------- +| id | main_id |赌注库尔斯|摘要is_sync |+ ---------------- + ---------------- + ------- + ------- -+ --------- + --------- +| 70003020040132 | 70003020038511 | | 0.0000 | 1798.00 | 0 |+ ---------------- + ---------------- + ------- + ------- -+ --------- + --------- +
但是当我通过perl :: DBI模块获得此数据时，我失去了精度，并且0.0000和1798.00的值分别变为0和1798。
下一个代码：
####
#These 3 subs are connecting to DB, executing query and get data by fetchall_arrayref and coverting undef to NULL.
####
sub DB_connect {
# DataBase Handler
my $dbh = DBI->connect("DBI:mysql:$DBNAME", $DBUSER, $DBPWD,{RaiseError => 0, PrintError => 0, mysql_enable_utf8 => 1}) or die "Error connecting to database: $DBI::errstr";
return $dbh;
}
sub DB_executeQuery {
# Executes SQL query. Return reference to array, or array, according to argv[0]
# argv[0] - "A" returns array, "R" - reference to array
# argv[1] - DB handler from DB_connect
# argv[2] - query to execute
my $choice=shift @_;
my $dbh=shift @_;
my $query=shift @_;
print "$query\n" if $DEBUG>2;
my $sth=$dbh->prepare($query) or die "Error preparing $query for execution: $DBI::errstr";
$sth->execute;
my $retval = $sth->fetchall_arrayref;
if ($choice eq "A" ) {
my @ret_arr=();
foreach my $value (@{ $retval }) {
push @ret_arr,@{ $value };
}
return @ret_arr;
}
elsif ($choice eq "R") {
return $retval;
}
}
sub undef2null {
# argv[1] - reference ro array of values where undef
# values has to be changed to NULL
# Returns array of prepared values: (...) (...) ...
my $ref=shift @_;
my @array=();
foreach my $row (@{ $ref }) {
my $str="";
foreach my $val ( @{ $row} ) {
if (! defined ( $val )) {
$str="$str, NULL";
}
else {
# Escape quotes and other symbols listed in square brackets
$val =~ s/([\"\'])/\\$1/g;
$str="$str, \'$val\'";
}
}
# Remove ', ' at the beginning of each VALUES substring
$str=substr($str,2);
push @array,"($str)";
} # End foreach my $row (@{ $ref_values })
return @array;
} # End undef2null
#### Main call
#...
# Somewhere in code I get data from DB and print it to out file
my @arr_values=();
my @arr_col_names=DB_executeQuery("A",$dbh,qq(SELECT column_name FROM `information_schema`.`columns` WHERE `table_schema` = '$DBNAME' AND `table_name` = '@{ $table }'));
@arr_ids=DB_executeQuery("A",$dbh,qq(SELECT `id` FROM `@{ $table }` WHERE `is_sync`=0));
my $ref_values=DB_executeQuery("R",$dbh,"SELECT * FROM \`@{ $table }\` WHERE \`id\` IN(".join(",",@arr_ids).")");
@arr_values=undef2null($ref_values);
print FOUT "REPLACE INTO \`@{ $table }\` (`".join("`, `",@arr_col_names)."`) VALUES ".(join ", ",@arr_values).";\n";
因此，我得到下一个字符串：
替换为`pko_plat`（`id`，`main_id`，`debet`，`kurs`，`summ`，`is_sync`）值（'70003020040132'，'70003020038511'，''，'0'，' 1798'，“ 0”）
在DB中为0.0000-变为0，为1798.00，变为1798
Perl的DBI文档说，它按原样将数据获取到字符串中，没有进行任何翻译。但是，那么，谁舍入了价值呢？
user @ host：〜＃mysql -V-mysql Ver 14.14 Distrib 5.7.25-28，用于debian-linux-gnu（x86_64），使用在debian-9,9下运行的7.0 user @ host：〜＃uname -a- Linux 4.9.0-8-amd64＃1 SMP Debian 4.9.144-3.1（...
由于创建列的方式，您看到的舍入正在发生。