Question

我的表格如下所示

Regno      Date       Year Batch h1   h2   h3  h4    h5   Att
1138M0345  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0346  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0347  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0348  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0349  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0350  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0351  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0352  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0353  25-07-2013  3    1    P    P    P  NULL  NULL  NULL
1138M0343  25-07-2013  3    1    A    A    A  NULL  NULL  NULL
1138M0344  25-07-2013  3    1    A    A    A  NULL  NULL  NULL

字段 h1，h2，h3，h4，h5和att可以存储空值 att field是为了存储学生当天的出勤率。我需要在以下条件下用 P / A / 1/2 更新字段 att

1. 'P' if H1 through H5 contains 'P' (Meaning present for the whole day) 2. '1' if H1 through H3 contains 'P' (Meaning present for the first session) 3. '2' if H4 and H5 contains 'P' (Meaning present for the second session) 4. NULL if any of H1 through H5 contains NULL (Meaning table needs to be updated completely) 5. Else 'A' (Meaning absent for the whole day)

任何人都可以帮助我解决逻辑

Answer 1

这是一个将更新指定日期范围的表的查询

DECLARE @StartDate datetime
DECLARE @EndDate datetime

SET @StartDate = '07/01/2013'
SET @EndDate = '07/26/2013'

UPDATE StudentAttendance
SET Att = 
 (
    CASE
       WHEN (H1 is null) or (H2 is null) or (H3 is null) (H4 is null) (H5 is null) THEN NULL
       WHEN H1='P' and H2='P' and H3='P' and H4='P' and H5='P' THEN 'P'
       WHEN H1='P' and H2='P' and H3='P' THEN 'P'
       WHEN H4='P' and H5='P' THEN 'P'
       ELSE 'A' 
    END
)
WHERE Date BETWEEN @StartDate and @EndDate

Answer 2

您也可以编写SQL查询

select [Regno], [Date], [Year], [Batch] as KEY,
case 
when 
(ISNULL(H1,'')='' OR ISNULL(H2,'')='' 
OR ISNULL(H3,'')='' OR ISNULL(H4,'')='' 
OR ISNULL(H5,'')='') THEN NULL
when (H1='P' and H2='P' and H3='P' and H4='P' and H5='P') THEN 'P'
when (H1='P' and H2='P' and H3='P') THEN 'P'
when (H4='P' and H5='P') THEN 'P'
ELSE 'A' END as APP
from Table1

<强> SQL Fiddle

Answer 3

如果我要获取一个值并首先插入表中，我会编写逻辑来查找特定学生的值（无论是p，a，1/2 ..）然后我会启动sql部分来更新在sql查询中找到的值....

说要更新1138M0345的att

我会使用select ... where regNo ='1138M0345'和Date ='ur date'来获取该记录
检查condition声明
存储上一步的结果，然后关闭查询
打开另一个查询（主要是更新语句，其中regNo = 1138M0345），并更新'att'

Answer 4

有效的查询是

UPDATE student_attendance_table SET att = 
  CASE 
    WHEN (h1 IS NULL) or (h2 IS NULL) or (h3 IS NULL) or (h4 IS NULL) or (h5 IS NULL) THEN NULL 
    WHEN h1='P' and h2='P' and h3='P' and h4='P' and h5='P' THEN 'P' 
    WHEN h1='P' and h2='P' and h3='P' THEN '1' 
    WHEN h4='P' and h5='P' THEN '2' 
    ELSE 'A' 
  END 
WHERE regno='" & reg & "' AND date='" & dtp1.Text & "' AND year=" & year & " AND batch= " & batch &"

复杂逻辑更新sql server中的表

4 个答案: