最近刚在搞一个BI的项目，里面需要大量的sql 数据统计相关运用，加深了我又对SQL的理解与使用。
所以，分享几个数据统计时常用的sql 语句总结：
1. 统计各个条件下的数据
select
BatchId,sum(CardSum) 总金额,
sum(case when Status= then CardSum else end) as 已使用,
sum(case when Status= then CardSum else end) as 已冻结
from GiftCard
group by BatchId
2. 统计每日,每月,每年的数据
select year(AddTime) 年,month(AddTime) 月,day(AddTime) 日,COUNT() 数量,sum(CardSum) 销售合计
from GiftCard
group by year(AddTime),month(AddTime),day(AddTime)
3. 某列去重统计
select COUNT(BatchId),COUNT(distinct BatchId),COUNT(distinct BatchName)
from GiftCard
4. 行转列
SELECT *
FROM (
SELECT
BatchName,
CardSum as TotAmount
FROM GiftCard ) as s
PIVOT
(
SUM(TotAmount)
FOR BatchName IN (zx测试商品, test新人优惠券,测试高考大放送)
)AS MyPivot
5. 得到表中最小的未使用的ID号
SELECT
(CASE WHEN EXISTS(SELECT * FROM GiftCard b WHERE b.Id = ) THEN MIN(Id) + ELSE END) as Id
FROM GiftCard WHERE NOT Id IN (SELECT a.Id - FROM GiftCard a)
6. 查询某一列数据不重复的数量
select *
from GiftCard a
where not exists(select from GiftCard where BatchName=a.BatchName and ID<a.ID)
7. 按年统计1月到12个月的销量
select year(AddTime) as '年',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '一月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '二月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '三月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '四月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '五月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '六月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '七月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '八月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '九月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '十月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '十一月',
SUM(case when MONTH(AddTime)= then CardSum else end ) as '十二月' from GiftCard group by year(AddTime)