使用TSQL，我可以增加一个CHAR（1）列一个，并用它在一个LEFT OUTER JOIN没有一个CASE语句？ [英] Using TSQL, can I increment a CHAR(1) column by one and use it in a LEFT OUTER JOIN without a CASE statement?
问题描述
这个问题类似于我的<一个href="http://stackoverflow.com/questions/899502/can-i-use-sql-to-find-missing-numbers-in-the-example-table-i-give-below">last问题。除了这一次我使用的字母，而不是6位整数。我想找到走出序列字母。
This question is similar to my last question. Except this time I'm using letters rather than 6 digit integers. I want to find the out of sequence "letters".
让我们说我有以下数据：
Let's say I have the following data:
id | Date | Letter
-----------------------------
01 | 5/1/2009 | X
02 | 5/1/2009 | Y
03 | 5/1/2009 | Z
04 | 5/1/2009 | A
05 | 5/1/2009 | B
06 | 5/1/2009 | D
我想能够拿出一个查询，会告诉我应该有一排05和06之间的一排C。
I would like to be able to come up with a query that would tell me there should be a row with "C" in between row 05 and 06.
在我的最后一个问题（使用int）我提供类似于下面的解决方案的东西，和它的工作太棒了。
In my last question (using INTs) I was offered something similar to the following solution, and it worked great.
SELECT * from TABLE1 t1
LEFT OUTER JOIN TABLE2 t2 ON t2.INTCol - 1 = t2.INTCol AND t1.date = t2.date
WHERE t2.id IS NULL
那么，与字母（据我所知）我不能说（G - 1）。因此，有另一种方式我可以做到这一点？
Well, with letters (as far as I know) I can't say (G - 1). So, is there another way I can do this?
我使用的数据库为SQL Server 2005。我相信这是在PL / SQL使用翻译一个简单的解决方案，但我没有，我可以做任何事情，就像使用TSQL的事情。
The database I am using is SQL Server 2005. I believe there is an easy solution in PL/SQL that uses TRANSLATE, but I don't thing I can do anything like using TSQL.
推荐答案
您可以在CHAR（1）利用转换成它的ASCII数
You can convert the char(1) to its ascii number using
ASCII(Letter)
您可以通过再增加一本，并返回到使用CHAR（如有必要）的信中，这样你的code会是这样的：
You can then increment this by one and return it to a letter using CHAR (if necessary), so your code would be this:
SELECT * from TABLE1 t1
LEFT OUTER JOIN TABLE2 t2
ON ASCII(t1.INTCol) - 1 = ASCII(t2.INTCol)
AND t1.date = t2.date
WHERE t2.id IS NULL
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