我确信这已经被讨论过很多次了,所以请原谅我的重复。我有一个有效的查询,但当前在一个选择中有 6 个 CASE 语句。有人提到,最好的优化方法是将所有 WHEN 条件放在一个 CASE 中。但是,我无法实现这一点
select right(RTRIM(region),5) as cell_id,
sum(CASE WHEN LEFT(cparty,3) in ('999','998','997') THEN chargeduration/60 else 0 END) AS OnNet_Minutes,
sum(CASE WHEN LEFT(cparty,3) in ('996','995') THEN chargeduration/60 else 0 END) AS OffNet_C_Minutes,
sum(CASE WHEN LEFT(cparty,3) in ('994','993','992') THEN chargeduration/60 else 0 END) AS OffNet_A_Minutes,
sum(CASE WHEN LEFT(cparty,3) in ('991','990') THEN chargeduration/60 else 0 END) AS OffNet_S_Minutes,
sum(CASE WHEN LEFT(cparty,2) = '00' THEN chargeduration/60 else 0 END) AS OffNet_T_Minutes,
sum(CASE WHEN len(cparty) < 6 and LEFT(cparty,1) <> 0 THEN chargeduration/60 else 0 END) AS SC_Minutes
from August.dbo.cdr20130818
where CHARGEDURATION > 0 and ISNULL(region,'''')<>'''' and LEN(region) > 5
group by right(RTRIM(region),5)
order by right(RTRIM(region),5) asc