SQL 数据小练习，呼叫中心 ----查询通话时间最长的5条记录 ----查询以0开头的通话总时,以秒为计算单位 ----查询2010年7月通话总时长最多的前两个呼叫员的编号 ----查询201

--CREATE TABLE [CallRecords]

--(

-- [Id] [int] NOT NULL identity(1,1),

-- [CallerNumber] [nvarchar](50), --三位数字，呼叫中心员工编号（工号）

-- [TelNum] [varchar](50),

-- [StartDateTime] [datetime] NULL,

-- [EndDateTime] [datetime] NULL  --结束时间要大于开始时间,默认当前时间

--)

----主键约束

--alter table [CallRecords]

--add constraint PK_CallRecords primary key(id)

----检查约束

--alter table [CallRecords]

--add constraint CK_CallRecords check(CallerNumber like '[0-9][0-9][0-9]')   

--alter table [CallRecords]

--add constraint CK_CallRecords_EndDateTime check(EndDateTime > StartDateTime)

----默认约束

--alter table [CallRecords]

--add constraint DF_CallRecords default(getdate()) for EndDateTime

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '0208888888', CAST(0x00009DAF00A4CB80 AS DateTime), CAST(0x00009DAF00A62E94 AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '0208888888', CAST(0x00009DB000D63BC0 AS DateTime), CAST(0x00009DB000D68DC8 AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '89898989', CAST(0x00009DB000E85C60 AS DateTime), CAST(0x00009DB000E92F50 AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('002', '98987676', CAST(0x00009DB2015BB7A0 AS DateTime), CAST(0x00009DB2015C4DA0 AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('002', '02188839389', CAST(0x00009DA4014C9C70 AS DateTime), CAST(0x00009DA4014E0308 AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '767676766', CAST(0x00009DB400DAA0C0 AS DateTime), CAST(0x00009DB400DD5FE0 AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('003', '0227864656', CAST(0x00009DB200B9AB40 AS DateTime), CAST(0x00009DB200B9FC1C AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('003', '676765777', CAST(0x00009DB8014042B8 AS DateTime), CAST(0x00009DB80141804C AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('001', '89977653', CAST(0x00009D9A00FB9898 AS DateTime), CAST(0x00009D9A00FE6118 AS DateTime));

--INSERT [dbo].[CallRecords] ([CallerNumber], [TelNum], [StartDateTime], [EndDateTime]) VALUES ('004', '400400400', CAST(0x00009D9A00FB9898 AS DateTime), CAST(0x00009D9A00FE6118 AS DateTime));

select * from dbo.CallRecords

----查询通话时间最长的5条记录

use test

go

select top 5 Id,CallerNumber,DATEDIFF

(second,startdatetime,enddatetime) as dutime

from CallRecords 

order by dutime desc

----查询以0开头的通话总时,以秒为计算单位

select
SUM(datediff(second,startdatetime,enddatetime))

from CallRecords

where TelNum like '0%'

----查询2010年7月通话总时长最多的前两个呼叫员的编号

select 

top 2

CallerNumber, 
sum(datediff(second,startdatetime,enddatetime)) as 时长,
count(*) as 电话数

 from CallRecords

where DATEDIFF(MONTH,'2010-7-1',startdatetime)=0

group by CallerNumber

order by 时长 desc

----查询2010年7月拨打电话次数最多的前两个呼叫员的编号

select 

top 2

CallerNumber, 
sum(datediff(second,startdatetime,enddatetime)) as 时长,
count(*) as 电话数

 from CallRecords

where DATEDIFF(MONTH,'2010-7-1',startdatetime)=0

group by CallerNumber

order by 电话数 desc