2

因此，我很高兴使用一个非常古老的数据库，该数据库显然是在规范化发明之前设置的。我被要求看看我是否能想出一个让它正常工作的方法。

第一个表实际上有一个真正的主键。例子：

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

问题是另一张桌子...

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

这些表是如何连接到他们的系统中的？是的，X 在行中的位置。因此，如果 X 在第一个位置，则为原因 1，第二个位置，原因 2，依此类推。它本质上是一个平面阵列。如果他们将其限制为每行 1 X，那实际上并不会太糟糕......（LOCATE('X', REASONS) as XINDEX）但事实并非如此。理论上，每行可以检查 21 个可能的 X。

所以我必须给他们一个关于如何让它发挥作用的建议。
我的第一个建议是创建一个单独的表并规范化这些表，但是我不知道这将如何进行，或者他们是否愿意更改他们的系统。
所以，我还想建议一个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，但我充满希望。

编辑

所以，是的，我真的要推动链接表。
这是我从建议中得到的替代方案： 

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

我将不得不稍微考虑一下 Marlin 的建议，看看它简化了多少，但我喜欢这个查询的一件事是它显示了他们当前的布局是多么荒谬，以及他们为什么应该改变它。

4

2 回答 2

1

我要做的第一件事是为 X 的每个可能位置创建一个新列（所以如果有 10 个位置 -> 10 个新列）并为这些列赋予有意义的名称。那么您可以更轻松地编写查询...

于 2012-10-11T17:45:39.847 回答
1

我真的会推销新的链接表，但这里要么是存储过程的核心，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'
于 2012-10-11T17:57:28.000 回答