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Searching for Special Characters

Posted on 2003-11-11
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Last Modified: 2012-05-04
I am trying to write a validation routine where I would use PATINDEX/CHARINDEX to locate either valid or invalid characters in a varchar variable.  I am already checking for the presence of Upper Case characters, lower case characters, and numbers, but I am trying to locate special characters (by range, or group) without have to write a check for each special character individually.  

e.g., IF PATINDEX('%[!,@,#,$,%...]%', @Variable)>0

Is this even possible?  I thought that I had read somewhere that it was but just can't seem to locate it now.

Thanks,

MT
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Question by:tognettm
8 Comments
 
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Expert Comment

by:PaulBarbin
ID: 9724857
Try something like this:

SELECT PATINDEX ('%[' + char(32) + '-' + char(64) + ']%', 'ad;kajsdf;lkjadfioeuroieur&adsfadf')

Paul
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Expert Comment

by:PaulBarbin
ID: 9724872
The code above gives you the ability to select a range of values.  Run the code below to check out the values that you need to use.

DECLARE @asc int
SET @asc = 0

WHILE @asc < 128
BEGIN
      PRINT CHAR(@asc) + ', ' + str(@asc)
      SET @asc = @asc + 1
END

hth
Paul
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Expert Comment

by:Lowfatspread
ID: 9725205
you basically had it

PATINDEX('%[!@#$,...]%', @Variable)>0

you don't need comma to separate the values....

if you want to search for % or _  or [ or ] then you need to define an escape character (or double up the [] eg [[])


PATINDEX('%[!@#$%%,...]%', @Variable) ESCAPE '%' >0


so the first % in the [ ] means that the second % is looked for as a percent sign...

hth



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Expert Comment

by:Scott Pletcher
ID: 9725397
Paul's approach looks generally good to me if you want to do checks for range(s) of characters.

But what do you mean by "valid", "invalid" and "special characters"?  Other than letters, upper and lower case, and numbers, what characters do you want to consider "valid"?
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Author Comment

by:tognettm
ID: 9728044
Paul's answer meets my needs for the orginal portion of the question and I will be awarding him the original 250 points.  Thanks.  

I would like to add more to this though, along the same lines and am increasing the point value as a result.

In looking for the valid Upper Case range of letters...

 IF patindex ('%[A-H]%','micHael1')<1
   Begin
   ...
   End,

The return results of PATINDEX is 3...this represents the letter 'c' (lower case) in the above string.  The same is true when I change the range values as follows:

IF PATINDEX('%['+CHAR(67)+'-'+CHAR(90)+']%','micHael1')
 
What gives?  What I am looking for here is to search the string for the presence of at least one Upper Case letter, and I will also be doing the same for a lower case letter.  Both need to be present.  

 Should I ask this as a separate question or is increasing the points then splitting them amongst the experts here enough since this addition is related to the first problem.  

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Expert Comment

by:Scott Pletcher
ID: 9731560
That's a bear.  AFAIK, on a case-insensitive installation, you would have to call a custom function to take case into consideration.
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Accepted Solution

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PaulBarbin earned 500 total points
ID: 9731817
Scott, I thought it was a collation problem too, but I can't seem to get it to work even when I explicitly set the collation for the literal (SQL 2K).

Am I doing something wrong here?

DECLARE @name varchar(30), @pattern varchar(30)

SET @name = 'micHael1' COLLATE LATIN1_GENERAL_CS_AS
SET @pattern = '%[A-H]%' COLLATE LATIN1_GENERAL_CS_AS

SELECT patindex (@pattern,@name)

Paul
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