SQL Case When Then Else End的使用收集

需求:

日志(info_log)里面包含多条录音记录(info_record)

员工表
info_user
user_id user_name

日志表
info_log
log_id user_id is_succ(成功1、失败0)

录音表
info_record
record_id log_id record_len

现需要统计每一个人员成功通话的长度、失败通话的长度、总的通话长度。下面是我使用的方法：

1.创建相关表

------创建用户信息表-------------
IF EXISTS (SELECT * FROM sysobjects  WHERE  [name]='sys_user')
DROP TABLE sys_user
BEGIN
CREATE TABLE sys_user(
[user_id] INT IDENTITY(1,1) PRIMARY KEY NOT NULL,
[user_name] NVARCHAR(20) NOT NULL
)
END
GO
-----------创建日志表---------------------
IF EXISTS (SELECT * FROM sysobjects s WHERE [name]='info_log')
DROP TABLE info_log
BEGIN
CREATE TABLE info_log
(
log_id INT PRIMARY KEY IDENTITY(1,1) NOT NULL,
[user_id] INT NOT NULL,
is_success BIT --1成功，0--失败
)
END
GO

-----------创建录音表-----------------------------
IF EXISTS (SELECT * FROM sysobjects s WHERE [name] ='info_record')
DROP  TABLE info_record
BEGIN
CREATE TABLE info_record(
record_id INT PRIMARY KEY IDENTITY(1,1) NOT NULL,
log_id INT NOT NULL,
record_len FLOAT NOT NULL
)
END
GO

2.插入测试数据

BEGIN
INSERT into sys_user ([user_name]) VALUES('Jack')
INSERT into sys_user ([user_name]) VALUES('Tom')
INSERT into sys_user ([user_name]) VALUES('Harry')
INSERT into sys_user ([user_name]) VALUES('Potter')
END
GO
--------------日志表插入数据----------------------
INSERT INTO info_log ([user_id],is_success) VALUES (1,1)
INSERT INTO info_log ([user_id],is_success) VALUES (1,0)
INSERT INTO info_log ([user_id],is_success) VALUES (2,1)
INSERT INTO info_log ([user_id],is_success) VALUES (2,0)
INSERT INTO info_log ([user_id],is_success) VALUES (3,1)
INSERT INTO info_log ([user_id],is_success) VALUES (3,0)
INSERT INTO info_log ([user_id],is_success) VALUES (4,1)
INSERT INTO info_log ([user_id],is_success) VALUES (4,0)
--------------插入录音数据-----------------------------
INSERT info_record (log_id,record_len)VALUES(1,10.08)
INSERT info_record (log_id,record_len)VALUES(2,11.18)
INSERT info_record (log_id,record_len)VALUES(3,9.08)
INSERT info_record (log_id,record_len)VALUES(4,8.2)
INSERT info_record (log_id,record_len)VALUES(5,7.08)
INSERT info_record (log_id,record_len)VALUES(6,2.08)
INSERT info_record (log_id,record_len)VALUES(7,3.08)
INSERT info_record (log_id,record_len)VALUES(8,5.08)
INSERT info_record (log_id,record_len)VALUES(9,4.08)
INSERT info_record (log_id,record_len)VALUES(10,5.08)

3.实现统计每一个人员成功通话的长度、失败通话的长度、总的通话长度

SELECT su.[user_name],SUM(CASE WHEN il.is_success=1 THEN  ir.record_len ELSE 0 END ) AS '成功通话长度',
sum(case when il.is_success=0 then ir.record_len else 0 end) as'失败通话长度',
SUM(ir.record_len) AS '总通话长度'
FROM sys_user su
LEFT JOIN info_log il ON il.[user_id] = su.[user_id]
LEFT JOIN info_record ir ON ir.log_id = il.log_id
GROUP BY su.[user_name]

希望博友如有更好的方法，写下来探讨一下。