count(*) 不 return 0

Question

我有一个 sql 问题，请帮助我，这是我的查询

  select count(category_value .list_value_id) as jobs , category_type.value as category
from list_values category_type
full outer join params category_value
on category_type.list_value_id = category_value .list_value_id
join qrtz_triggers jobs
on category_value .object_id = jobs.job_name
and jobs.trigger_state ='PAUSED'
and category_value.attr_id = 9158075153713931109
where category_type.attr_type_def_id = 9158075154713931109
group by category_type.value;

attr_id 是列表值，其中包含 9158075158713931109（非关键）和 9158075157713931109（关键）

returns result:
JOBS,   CATEGORY
2        Non-Critical


expected result is :
JOBS,   CATEGORY
2        Non-Critical
0          Critical

list_values table conains
list_value_id          values
9158075158713931109     non-critical
9158075157713931109      critical


params table
list_value_id          attr_id                         object_id
9158075158713931109     9158075153713931109           a
9158075157713931109      9158075153713931109          b
9158075157713931109      9158075153713931109          c
9158075158713931109     9158075153713931109           d

qtz_trigger table  i need triggers with state "paused"

job_name            trigger_state 
b                     paused
a                     paused
e                     normal
c                     paused

我什至尝试了 category_value .object_id in (select jobs.job_name from qrtz_triggers jobs where jobs.trigger_type ='SIMPLE') 但收到错误命令未正确结束

Answer 1

本次过滤条件：

where category_type.attr_type_def_id = 9158075154713931109

将把 full join 变成左连接或右连接。

使用 full joins 过滤非常棘手。我不确定是否需要 full join - 你的问题并没有解释你真正想做什么。但是，如果您确实需要 full join，我发现在子查询中进行过滤通常可以满足我的要求。

Answer 2

我认为你实际上想要 left joins，从 list_values table 开始，然后加入 params 和 qrtz_triggers:

select count(t.job_name) as jobs, v.value as category
from list_values v
left join params p
    on  p.list_value_id = v.list_value_id
    and p.attr_id       = v.attr_type_def_id
left join qrtz_triggers t
    on  t.job_name      = p.object_id
    and t.trigger_state = 'PAUSED'
where v.attr_type_def_id = 9158075154713931109
group by v.value;

原始查询中的条件有点混乱，所以我尝试 re-arrange - 您可能需要查看它。我还使用了简短且具有代表性的 table 别名。

count(*) 不 return 0

count(*) doesn't return 0

sql

count

left-join

full-outer-join