[英]Selecting distinct values from key/value pairs in a seperate table
I have 2 database tables 我有2个数据库表
JOBS(JOB_ID, JOB_TIME, JOB_NAME,...), JOB_PARAMETERS(JOB_ID,NAME,VALUE)
where JOB_PARAMETERS is essentially a map containing job parameter key value pairs. 其中JOB_PARAMETERS本质上是一个包含作业参数键值对的映射。 Every job may have a unique parameter key/value pairs.
每个作业可能具有唯一的参数键/值对。
I am looking to pragmatically build a query that will return distinct job id's that contain key/value combinations. 我期待以实用的方式构建一个查询,该查询将返回包含键/值组合的不同作业ID。 Where the values are actually a list of values, comparison operators.
其中值实际上是值列表,比较运算符。 For example:
例如:
JOB_PARAMETERS: NAME = 'OUTPUT_FILENAME', VALUE LIKE "ALEX%", "JAX%"
NAME = 'PRIORITY' , VALUE > 7
The above example would automatically filter out all jobs that don't have the OUTPUT_FILENAME and PRIORITY key. 上面的示例将自动过滤掉所有没有OUTPUT_FILENAME和PRIORITY键的作业。 Returning All jobs that meet both conditions.
返回满足这两个条件的所有工作。
I also need to be able to support pagination and order by. 我还需要能够支持分页和排序。
I was planning on using Perl with DBIx::Class, But I can do it in pure Perl/SQL as well. 我计划将Perl与DBIx :: Class一起使用,但我也可以在纯Perl / SQL中使用它。
I am open to changing the database schema, but every job can have different key/value pairs, so I cant just make them columns in the jobs table. 我愿意改变数据库模式,但每个作业都可以有不同的键/值对,所以我不能只在job表中创建它们。
Thanks in advance. 提前致谢。
One can do it in SQL, by grouping JOB_PARAMETERS
by JOB_ID
and filtering the groups accordingly. 可以在SQL中执行此操作,方法是将
JOB_PARAMETERS
按JOB_ID
分组并相应地过滤组。 For example, if there is a uniqueness constraint over (JOB_ID, NAME)
, one can query as follows: 例如,如果
(JOB_ID, NAME)
存在唯一性约束,则可以按如下方式进行查询:
SELECT JOB_ID
FROM JOB_PARAMETERS
WHERE (NAME='OUTPUT_FILENAME' AND (VALUE LIKE 'ALEX%' OR VALUE LIKE 'JAX%'))
OR (NAME='PRIORITY' AND VALUE > 7)
GROUP BY JOB_ID
HAVING COUNT(*) = 2
Absent such a uniqueness constraint, COUNT(*)
would have to be replaced eg with COUNT(DISTINCT NAME)
. 如果没有这样的唯一性约束,则必须用
COUNT(DISTINCT NAME)
替换COUNT(*)
COUNT(DISTINCT NAME)
。
When using DBIx::Class you can generate a DBIC schema by using Schema::Loader. 使用DBIx :: Class时,可以使用Schema :: Loader生成DBIC模式。
After connecting to the database you get a $schema object you can use to get a ResultSet filtered to return the Result objects you want: 连接到数据库后,您将获得一个$ schema对象,您可以使用该对象来过滤ResultSet以返回所需的Result对象:
my $rs_job_parameters = $schema->resultset('Job_Parameters')->search({
-or => [
{
'name' => 'OUTPUT_FILENAME',
'value' => [{ like => 'ALEX%'}, { like => 'JAX%' }].
},
{
'name' => 'PRIORITY',
'value' => [{ '>' => 7}].
}
]},
{
columns => [qw( job_id )],
group_by => [qw( job_id )], # alternative you can use distinct => 1 to group_by all selected columns
having => \[ 'COUNT(*) = ?', [ 2 ] ],
}
);
my @job_ids = $rs_job_parameters->get_column('job_id')->all;
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