Question

请帮我解决这个问题。我想找到员工数量的员工人数。从员工表中的T和N开始，按表分组。查询如下：

select
    m.institution_dist,
    count(e.emp_pf_acc_number like 'T%') as tcnt,
    count(e.emp_pf_acc_number like 'N%') as ncnt 
from
    pf_emp e
    left join
    pfmast_institution m on e.emp_workplace_code = m.institution_code 
where
    e.retired <> 'Y'
    and emp_classification_code = '3'
    and m.institution_dist in (
        select dist_name
        from pfmast_dist
    )
group by m.institution_dist

问题在于，我得到的结果与从T和N开始的员工相同。

Answer 1

只需将or null添加到计数表达式

即可

count(e.emp_pf_acc_number like 'T%' or null) as tcnt,
count(e.emp_pf_acc_number like 'N%' or null) as ncnt

count计数不为空。当您的原始表达式返回true或false时，它将始终被计算在内。 false or null评估为null，因此不计算在内。

where子句

有优化

and exists (
    select 1 
    from pfmast_dist
    where m.institution_dist = dist_name
)

Answer 2

尝试此查询：

Select * from  

(select m.institution_dist, 
        Count(e.emp_pf_acc_number like 'T%') as tcnt  
from  pf_emp e 
left join   
pfmast_institution m     on e.emp_workplace_code = m.institution_code 
 where e.retired <> 'Y'    
 and emp_classification_code = '3'
 and m.institution_dist in ( select dist_name from pfmast_dist)
group by m.institution_dist ) x 

full outer join

(select b.institution_dist,count(a.emp_pf_acc_number like 'N%') as ncnt 
from pf_emp a
 left join
 pfmast_institution b on a.emp_workplace_code = b.institution_code 
 where b.retired <> 'Y'
 and emp_classification_code = '3'
 and b.institution_dist in ( select dist_name from pfmast_dist )
 group by b.institution_dist) y 
on x.institution_dist = y.institution_dist

从T和N开始的员工编号

2 个答案: