Php 行间时间差

我必须遵循图1下面的查询，这是可行的，但我想做的是得到第4行和第5行之间的时间差，然后得到第5行和第6行之间的差

其目的是在查询中获得类似图2的内容，理想情况下，我希望这样做，而不必在数据库中的每一行循环，然后返回PHP

提前谢谢

图1

图2预期结果

| ID  | Module | MoudleStatus            | UpdatedOn           | Diff(days)

|   4 | LW2205 | Draft exam received     | 2017-10-18 12:41:12 | 0

|   5 | LW2205 | Draft exam received     | 2017-10-18 12:41:23 | 0

|   7 | LW2205 | Draft exam received     | 2017-10-20 15:06:46 | 2

| 275 | LW2205 | Exam approved by Dean   | 2017-11-14 16:39:28 | 24

| 288 | LW2205 | Final exam sign off by  | 2017-11-21 12:28:59 | 7

| 295 | LW2205 | Exam sent to SREO (Stud | 2017-11-23 09:53:30 | 3

+-----+--------+-------------------------+---------------------+

---

此SQL代码适用于应用于图1中的表：

SELECT
  t1.ID,
  t1.Module,
  t1.MoudleStatus,
  t1.UpdatedOn,
  IFNULL(DATEDIFF(
    t1.UpdatedOn,
    (SELECT MAX(t2.UpdatedOn) FROM ModuleFlowModuleStatus AS t2 WHERE t2.id < t1.id)
  ), 0) AS `Diff(Days)`
FROM
  ModuleFlowModuleStatus AS t1;

---

代码可以优化/改进一点，但对我来说很有用。为了简化代码，我省略了WHERE和ORDERBY子句，您只需再次添加它们。如果有帮助，请告诉我。哦，MySQL DATEDIFF函数默认以天为单位返回值，我认为这正是您想要的。

另一种方法是分配行号并加入

SELECT T.*, S.RN1,S.UPDATEDON,
         DATEDIFF(t.UPDATEDON,s.UPDATEDON) DIFF
FROM
(
SELECT T.*, 
         IF(T.MODULE <> @P , @RN:=1,@RN:=@RN+1) RN,
         @P:=T.MODULE P
FROM T
CROSS JOIN (SELECT @RN:=0,@P:='') R
where t.Module = 'LW2205'
order by t.module, t.id
)T 
LEFT JOIN
( 
SELECT T.*, 
         IF(T.MODULE <> @P1 , @RN1:=1,@RN1:=@RN1+1) RN1,
         @P1:=T.MODULE P1
FROM T
CROSS JOIN (SELECT @RN1:=0,@P1:='') R
where t.Module = 'LW2205'
order by t.module, t.id
) S
ON S.RN1 = T.RN - 1 AND S.MODULE = T.MODULE;

---

注意，结果与您预期的结果不同

您使用的是哪个版本的mysql？我使用的是5.1.73DiffDays版本-需要删除括号或用单引号括起来以避免语法错误，谢谢您的提示@p.Salmon。代码更正：DiffDays逃脱了。谢谢各位。。。非常感谢。。。我正在寻找一种方法来做到这一点。。。我会试试，然后再回来。。。。谢谢

| ID  | Module | MoudleStatus            | UpdatedOn           | Diff(days)

|   4 | LW2205 | Draft exam received     | 2017-10-18 12:41:12 | 0

|   5 | LW2205 | Draft exam received     | 2017-10-18 12:41:23 | 0

|   7 | LW2205 | Draft exam received     | 2017-10-20 15:06:46 | 2

| 275 | LW2205 | Exam approved by Dean   | 2017-11-14 16:39:28 | 24

| 288 | LW2205 | Final exam sign off by  | 2017-11-21 12:28:59 | 7

| 295 | LW2205 | Exam sent to SREO (Stud | 2017-11-23 09:53:30 | 3

+-----+--------+-------------------------+---------------------+

+------+--------+-------------------------+---------------------+------+--------+------+---------------------+------+
| ID   | Module | MoudleStatus            | UpdatedOn           | RN   | P      | RN1  | UPDATEDON           | DIFF |
+------+--------+-------------------------+---------------------+------+--------+------+---------------------+------+
|    4 | LW2205 | Draft exam received     | 2017-10-18 12:41:12 |    1 | LW2205 | NULL | NULL                | NULL |
|    5 | LW2205 | Draft exam received     | 2017-10-18 12:41:23 |    2 | LW2205 |    1 | 2017-10-18 12:41:12 |    0 |
|    7 | LW2205 | Draft exam received     | 2017-10-20 15:06:46 |    3 | LW2205 |    2 | 2017-10-18 12:41:23 |    2 |
|  275 | LW2205 | Exam approved by Dean   | 2017-11-14 16:39:28 |    4 | LW2205 |    3 | 2017-10-20 15:06:46 |   25 |
|  288 | LW2205 | Final exam sign off by  | 2017-11-21 12:28:59 |    5 | LW2205 |    4 | 2017-11-14 16:39:28 |    7 |
|  295 | LW2205 | Exam sent to SREO (Stud | 2017-11-23 09:53:30 |    6 | LW2205 |    5 | 2017-11-21 12:28:59 |    2 |
+------+--------+-------------------------+---------------------+------+--------+------+---------------------+------+
6 rows in set (0.00 sec)