Question

所以我很高兴能够使用一个非常古老的数据库，这个数据库显然是在标准化发明之前设置的。我被问到是否能想出办法让它正常工作。

第一个表实际上有一个真正的主键。例如：

ID, Reason
--- ----------
 1, Write off
 2, Overage
 3, OLH

问题出在另一张桌子上......

CustomerNum, JobNum, Reasons
------------ ------- ---------------------
      42351,     46, X
      32313,    456,    X
      85472,     13,   X    X

这些表如何加入他们的系统？是的，X在线上的位置。因此，如果X位于第一个位置，那么原因是1，第二个位置，原因2，依此类推。它本质上是一个平面阵列。如果他们将它限制在每行1 X ......（LOCATE('X', REASONS) as XINDEX），那实际上并不会很糟糕，但事实并非如此。从理论上讲，每行可以检查21种可能的X.

所以我必须向他们提出如何使其发挥作用的建议我的第一个建议之一是创建一个单独的表并对表进行规范化，但是我不知道它会有多好，或者他们是否愿意改变他们的系统。
所以，我还想建议类似于存储过程的东西，它能够遍历每一行并返回索引，就好像它们在一个单独的表中一样。

我不知道这是否可能，但我很有希望。

修改

所以是的，我真的要推送链接表这是我从建议中得到的另一种选择：

Select tblCustomers.*, 
CASE WHEN SUBSTRING(Reasons,1,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 1)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,2,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 2)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,3,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 3)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,4,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 4)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,5,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 5)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,6,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 6)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,7,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 7)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,8,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 8)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,9,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 9)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,10,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 10)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,11,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 11)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,12,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 12)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,13,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 13)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,14,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 14)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,15,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 15)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,16,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 16)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,17,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 17)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,18,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 18)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,19,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 19)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,20,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 20)) || ', ' ELSE '' END 
|| CASE WHEN SUBSTRING(Reasons,21,1) = 'X' THEN RTRIM((SELECT Reason FROM tblReasons WHERE ID = 21)) || ', ' ELSE '' END AS XPOS 
From tblCustomers

我将不得不玩Marlin的建议，看看它有多精简它，但我对此查询的一个看法是，它显示了当前布局是多么荒谬，以及为什么要更改它

Answer 1

我要做的第一件事就是为X的每个可能位置创建一个新列（所以如果有10个位置 - > 10个新cols）并给这些列提供有意义的名称。那么你可以更容易地编写查询......

Answer 2

我真的推销新的链接表，但这里要么是存储过程的主要内容，要么是填充链接表的方式：

SELECT Customers.CustomerNum, Reasons.ID
FROM Customers, Reasons
WHERE SUBSTR(Customers.Reasons, Reasons.ID, 1) = 'X'

DB2 - 为字符串中的字符获取多个位置的方法

2 个答案: