oracle 统计sql

最近在研究项目时发现如下sql,

select 3 agentOfGCount,
0 workingCount,
0 restingCount,
0 busyingCount,
0 connectingCount,
0 waitingCount,
0 callingCount,
batch.batch_num,
all_task.allcount,
finish_task.finish_count,
batch_order_group.work_order_id,
batch_order_group.work_order_name
from (select task.batch_id,
task.project_id work_order_id,
max(task.project_name) work_order_name,
task.group_id
from cc_call_task task
where task.task_type = 1
and task.group_id = 444
and task.project_id = 119
and task.task_status in (1, 2)
group by task.project_id, task.batch_id, task.group_id) batch_order_group
left join cc_batch_calledperson batch
on batch_order_group.batch_id = batch.batch_id
left join (select task.batch_id,
max(task.project_id) work_order_id,
count(*) finish_count
from cc_call_task task
where task.task_type = 1
and task.task_status = 3
and task.group_id = 444
group by task.batch_id) finish_task
on finish_task.batch_id = batch.batch_id
left join (select task.batch_id, count(*) allcount
from cc_call_task task
where task.task_type = 1
and task.task_status != 4
and task.group_id = 444
group by task.batch_id) all_task
on all_task.batch_id = batch.batch_id
where batch.batch_type in (1, 4)

咋一看还以为是写错了（红体字）后来才发现，原来是为了让返回的前几列中的值都是3,0,0,0，，，而后面紧跟的是别名，这样查出来的结果表一般用于统计显示更方便一些，呵呵，以后自己要留心了，，，