1 原表T1某条记录(记做r1，相邻下一条为r2)的下一行记录的STARTDATE小于上一行ENDDATE，针对这样的记录做转换即：
r1的STARTDATE保持不变，ENDDATE为r1的STARTDATE-1
r2的STARTDATE为r1的ENDDATE，ENDDATE为r1的ENDDATE
2 如果原表T1不存在相邻行“时间重叠”（即为1的定义）时保持原有数据不变。
# 文本版 #T1 seq id startdate enddate num 1 1 2021-04-20 2021-05-03 200 2 1 2021-05-01 2021-05-24 100 3 1 2021-05-18 2021-05-31 69 4 1 2021-05-20 2021-07-31 34 5 1 2021-08-05 2021-08-25 45 6 1 2021-08-15 2021-09-25 65 #输出结果 ID STARTDATE ENDDATE NUM 1 2021-04-20 2021-04-30 200 1 2021-05-01 2021-05-02 300 1 2021-05-03 2021-05-17 100 1 2021-05-18 2021-05-19 169 1 2021-05-20 2021-05-23 203 1 2021-05-24 2021-05-30 103 1 2021-05-31 2021-07-30 34 1 2021-08-05 2021-08-14 45 1 2021-08-15 2021-08-25 110 1 2021-08-26 2021-09-25 65
SEQ ID STARTDATE ENDDATE NUM 1 1 2021-04-20 2021-05-03 200 2 1 2021-05-01 2021-05-24 100 3 1 2021-05-18 2021-05-31 69 4 1 2021-05-20 2021-07-31 34
这里第4条记录同时叠加在第2和3条记录里。
1) T0 通过上下行函数生成的时间序列
id new_DATE nextSTARTDATE preEndDATE rn 1 2021-05-24 2021-05-03 1 1 2021-05-03 2021-05-24 2021-05-01 2 1 2021-05-01 2021-05-03 2021-04-20 3 1 2021-04-20 2021-05-01 4
2) last 取出T0里的最后一条记录，为后面的矫正做准备。
new_Date preENDDATE id 2021-05-24 2021-05-03 1
3) normal 取出原始数据里不会出现时间叠加的记录，为后面的矫正做准备。
当前演示数据无记录，代码加注释可浮现。
4）T_Serial 统一定义STARTDATE、ENDDATE，首次修正T0。
id STARTDATE ENDDATE 1 2021-04-20 2021-04-30 1 2021-05-01 2021-05-03 1 2021-05-04 2021-05-24
5) T2 对时间没有重叠的记录进行修正(删除T0对应值，更新对应ENDDATE)。
当前示例结果集为空，即无需要修正。
6) T2关联T1(原始表)，汇总后取得最终值
STARTDATE ENDDATE NUM 2021-04-20 2021-04-30 200 2021-05-01 2021-05-03 300 2021-05-04 2021-05-24 100
当前演示版本是Mysql 8.0.23，支持CTE、窗口函数的SQL Server、Oracle需要修改Order by和ADDDATE处语法。
Step0 创建表并初始化数据
DROP TABLE IF EXISTS test_ShenLiang2025;
CREATE TABLE test_ShenLiang2025 (
seq int DEFAULT NULL,
id int DEFAULT NULL,
STARTDATE date DEFAULT NULL,
ENDDATE date DEFAULT NULL,
NUM int DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
INSERT INTO test_ShenLiang2025 VALUES ('1', '1', '2021-04-20', '2021-05-03', '200');
INSERT INTO test_ShenLiang2025 VALUES ('2', '1', '2021-05-01', '2021-05-24', '100');
INSERT INTO test_ShenLiang2025 VALUES ('3', '1', '2021-05-18', '2021-05-31', '69');
INSERT INTO test_ShenLiang2025 VALUES ('4', '1', '2021-05-20', '2021-07-31', '34');
INSERT INTO test_ShenLiang2025 VALUES ('5', '1', '2021-08-05', '2021-08-25', '45');
INSERT INTO test_ShenLiang2025 VALUES ('6', '1', '2021-08-15', '2021-09-25', '65');
Step1 构建临时结果集以生成时间序列。
WITH T0 AS(
SELECT id,
new_DATE,
LEAD(NEW_DATE,1) OVER (PARTITION BY ID ORDER BY NEW_DATE ) nextSTARTDATE,
LAG(NEW_DATE,1) OVER (PARTITION BY ID ORDER BY NEW_DATE ) preENDDATE,
ROW_NUMBER()OVER(PARTITION BY ID ORDER BY new_DATE DESC) rn
FROM
(
SELECT DISTINCT ID,STARTDATE new_DATE FROM test_ShenLiang2025
WHERE seq in (1,2) -- 可加注释验证，当前仅取原表里2条记录
UNION
SELECT DISTINCT ID,ENDDATE new_DATE FROM test_ShenLiang2025
WHERE seq in (1,2) -- 可加注释验证，当前仅取原表里2条记录
ORDER BY new_DATE
)A
),last AS
( SELECT new_DATE,preENDDATE,id
FROM T0
WHERE nextSTARTDATE IS NULL
),normal AS
(
SELECT * FROM
(
SELECT id,
ENDDATE,
LEAD(STARTDATE,1) OVER (PARTITION BY ID ORDER BY ENDDATE ) nextSTARTDATE,
LAG(ENDDATE,1) OVER (PARTITION BY ID ORDER BY ENDDATE ) preENDDATE
FROM test_ShenLiang2025
)A
WHERE ENDDATE > preENDDATE AND ENDDATE < nextSTARTDATE
),T_Serial AS (
SELECT ID,ADDDATE(preENDDATE, INTERVAL 1 DAY ) STARTDATE,
new_DATE ENDDATE
FROM last
UNION
SELECT bottom_2.ID,bottom_2.new_DATE STARTDATE,
CASE WHEN rn =3 THEN bottom_2.nextSTARTDATE
ELSE ADDDATE(bottom_2.nextSTARTDATE, INTERVAL -1 DAY ) END ENDDATE
FROM last
JOIN T0 bottom_2
ON bottom_2.nextSTARTDATE<=last.preENDDATE AND bottom_2.id = last.id
),T2 AS(
SELECT B.ID,B.STARTDATE,B.ENDDATE FROM
(
SELECT A.*,ROW_NUMBER()OVER(PARTITION BY ID,STARTDATE ORDER BY ENDDATE) rn
FROM
(
SELECT A.ID,A.STARTDATE,A.ENDDATE
FROM T_Serial A
LEFT JOIN normal B
ON A.STARTDATE = B.ENDDATE AND A.ID = B.ID
WHERE B.ENDDATE IS NULL
UNION
SELECT A.ID,A.STARTDATE,B.ENDDATE
FROM T_Serial A
INNER JOIN normal B
ON ADDDATE(A.ENDDATE, INTERVAL 1 DAY ) = B.ENDDATE AND A.ID = B.ID
)A
)B WHERE rn =1
)
Step2 时间序列关联原表生成NUM字段。
SELECT T2.STARTDATE,T2.ENDDATE,SUM(T1.NUM) TOTAL FROM T2 JOIN test_ShenLiang2025 T1 ON T2.STARTDATE>=T1.STARTDATE AND T2.ENDDATE<=T1.ENDDATE GROUP BY T2.STARTDATE,T2.ENDDATE ORDER BY T2.STARTDATE
Step4 查看结果
STARTDATE ENDDATE NUM
2021-04-20 2021-04-30 200
2021-05-01 2021-05-03 300
2021-05-04 2021-05-24 100
执行结果：
