使用SUBSTRING和LEN的SQL问题

Question

SELECT [Code], [Due Date Calculation],

--original string that is causing the error
--SUBSTRING([Due Date Calculation], 1, LEN([Due Date Calculation]) - 1) as OG,

--here are the tests that run fine by themselves
LEN([Due Date Calculation]) - 1 as Test1,
SUBSTRING([Due Date Calculation], 1, 2) AS Test2, 
SUBSTRING([Due Date Calculation], 1, LEN([Due Date Calculation])) AS Test3 

FROM [TEST]

Here is the error I am getting:

Msg 537, Level 16, State 2, Line 1 Invalid length parameter passed to the LEFT or SUBSTRING function.

I know it has something to do with the way SQL is rendering the data. The data displays a small upside down 'L' when I query it using SQL, but it simply shows a 'D' in the front end. I don't have a good enough reputation to include the images. An example of a typical Codes are 30D , 60D , 120D , 365D , etc.

I need to drop the trailing D and display what is left.

Thanks for the help.

Here are the results from the SQL Query: [ https://drive.google.com/file/d/0B1cL-bzbZ4IzU2ctYlRNZnJhZjg/view?usp=sharing][1]

Answer 1

If i understand your problem correctly you are looking for this

Select SUBSTRING([Due Date Calculation],0,CHARINDEX('D',[Due Date Calculation])) 
As [Due Date Calculation]  FROM Test

SQLFIDDLE

Answer 2

Here is my sample

declare @tbl table
(
    c1 nvarchar(9)
)
insert into @tbl values ('30D')
insert into @tbl values ('120D')
insert into @tbl values ('365D')

select  IIF(RIGHT(c1, 1) = 'D', LEFT(C1, LEN(C1)-1), C1)
from    @tbl

Result
30
120
365

Answer 3

If you want to cut off the last character, just do it like this.

DECLARE @String VARCHAR(100) = '123D'

SELECT SUBSTRING(@String,0,LEN(@String))

Or if you have multiple characters at the end, then try this which will grab until the numbers stop.

DECLARE @String VARCHAR(100) = '123D'

SELECT SUBSTRING(@String,0,PATINDEX('%[^0-9]%',@String))

Both have same results:

123