小5聊Sql Server基础之统计库龄语句，仅作为语句使用

Posted 2022-04-18 小5聊

知识点的综合使用

分组、数据转换、Case when then、max、min、count、sum、left join多表关联等知识点

• 知识点

编号	知识点	说明
1	group by	对某个表字段进行分组
2	convert	数据类型转换
3	case when then else end	逻辑判断
4	max	最大值
5	min	最小值
6	count	记录数
7	sum	统计值，综合
8	left join	左链接

1、知识点

1）group by

此处以商品编号进行分组

select shopid from stock group by shopid

2）

 2）convert

数据类型转换，varchar(10)和120，datetime时间数据类型转为字符串，并只显示10位长度值，刚好就是yyyy-MM-dd

select convert(varchar(10),timevalue,120) as timevalue from stock

2、创建表

 

USE [test]
GO

/****** Object:  Table [dbo].[stock]    Script Date: 04/17/2022 10:52:02 ******/
SET ANSI_NULLS ON
GO

SET QUOTED_IDENTIFIER ON
GO

SET ANSI_PADDING ON
GO

CREATE TABLE [dbo].[stock](
	[typeValue] [varchar](50) NULL,
	[shopid] [int] NULL,
	[timevalue] [datetime] NULL,
	[stockValue] [int] NULL
) ON [PRIMARY]

GO

SET ANSI_PADDING OFF
GO

3、表添加记录

模拟一定量的记录进行测试

--truncate table stock
/*
insert into stock(typeValue,shopid,timevalue,stockValue)
values('入库',123,'2020-01-01',100)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('入库',234,'2020-01-02',100)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('出库',123,'2020-01-03',50)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('出库',234,'2020-01-04',50)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('出库',123,'2020-01-05',50)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('出库',234,'2020-01-06',50)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('入库',123,'2020-01-07',100)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('入库',234,'2020-01-08',100)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('出库',123,'2020-01-09',30)
insert into stock(typeValue,shopid,timevalue,stockValue)
values('出库',234,'2020-01-10',30)
*/

4、查询代码

/*
编号123，还存在库存，则使用上次进货时间2020-01-11和2020-02-20相差，就是40天
编号234，还存在库存，则使用上次进货时间2020-01-11和2020-02-20相差，就是41天'
*/

declare @searchTime varchar(50)
set @searchTime='2020-02-20'

select a.shopid as 商品编号,
convert(varchar(10),a.inMaxTime,120) as 上次进货时间,
@searchTime as 搜索时间,
(case when (a.totalInValue-b.totalOutValue)>0 
then datediff(day, a.inMaxTime, @searchTime) --还有库存，则用上次进货时间计算
else datediff(day, b.outMaxTime, @searchTime) end) as 库龄, --没有库存了，使用最后一次出库时间计算
(a.totalInValue-b.totalOutValue) as '库存',
(case when (a.totalInValue-b.totalOutValue)>0 then '还有库存' else '已出完' end) as 是否出库完
from(
    --先按商品编号分组，并筛选入库值和统计入库总值
    --出库最小得时间
    select shopid,
    min(timevalue) as inMinTime, --入库最小时间
    max(timevalue) as inMaxTime, --入库最大时间（上次进货时间）
    sum(stockValue) as totalInValue,
    count(1) as inCount
    from stock 
    where typeValue='入库' and timevalue<=@searchTime
    group by shopid
) as a
left join(
    select shopid,
    min(timevalue) as outMinTime, --出库最小时间
    max(timevalue) as outMaxTime, --出库最大时间
    sum(stockValue) as totalOutValue  --出库总数
    from stock where typeValue='出库' and timevalue<=@searchTime
    group by shopid
) as b
on a.shopid=b.shopid