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String Manipulation Get Count of Number of Occurrences of Character in String

Applicability:

                 SQL Server 2000:        Tested
                 SQL Server 2005:        Tested
                 SQL Server 2008:        Tested
                 SQL Server 2008R2:    Tested
                 SQL Server 2012:        Not Tested        

Credits:

Author:    ChillyDBA
Date:        17 Jul 2012

Description

Returns the count of all occurrences of the supplied character in the supplied string

Takes 3 parameters:
  • @Character - the character to be searched for
  • @String - the string to be searched
  • @IsCaseSensitive - 1 indicates that case sensitivity should be enforced during the search.  Default 0.  
NOTE1:  For case sensitivity (CS), this will enforce CS in a non-CS database but will not relax CS in a CS database
NOTE2:  The function utilises the function udf_NumbersTable.  This has several versions, depending on SQL Server version.  

Code

Function:


DROP FUNCTION dbo.udf_GetCountOfCharacterInString
GO

CREATE FUNCTION dbo.udf_GetCountOfCharacterInString
(
  
@Character          CHAR(1),            -- the character to search for
  
@String             VARCHAR(MAX),       -- the string to search
  
@IsCaseSensitive    BIT = 0               -- is the search honor case sensitive?
)
RETURNS INT

AS

/**********************************************************
Purpose:   Returns a count of the number of times the supplied
           character occurs at in the supplied string.
          
           NOTE:  The case sensitive flag will only cause case sensitivity (CS) to
           be applied in a non-CS DB.  If will not apply non-CS in a CS DB
          
           Utilises udf_NumbersTable to provide the required 'tally' table used
           when parsing the string for matches

Author:        ChillyDBA
History        17 Jul 2012 - Initial Issue

***********************************************************/

BEGIN
   DECLARE
@CountofOccurences INT

   IF
@IsCaseSensitive = 0
  
BEGIN      
       SELECT
@CountofOccurences = MAX(RowNumber)
      
FROM
      
(
          
SELECT ROW_NUMBER() OVER (ORDER BY i ASC) AS RowNumber
          
FROM dbo.udf_NumbersTable(1, DATALENGTH(@String), 1)  
          
WHERE i <= LEN(@String)    
           AND
SUBSTRING(@String,i,1) = @Character
      
) AS x
  
END
   ELSE
   BEGIN
       SELECT
@CountofOccurences = MAX(RowNumber)
      
FROM
      
(
          
SELECT ROW_NUMBER() OVER (ORDER BY i ASC) AS RowNumber
          
FROM dbo.udf_NumbersTable(1, DATALENGTH(@String), 1)  
          
WHERE i <= LEN(@String)    
           AND
ASCII(SUBSTRING(@String,i,1)) = ASCII(@Character)
       )
AS x
  
END
      
   RETURN
@CountofOccurences

END


Test Code:


SELECT dbo.udf_GetCountOfCharacterInString('e', ',Element01,Element02,Element03,Element04,Element05,', 0)
SELECT dbo.udf_GetCountOfCharacterInString('e', ',Element01,Element02,Element03,Element04,Element05,', 1)

ċ
udf_GetCountOfCharacterInString.sql
(2k)
Andy Hughes,
Jul 17, 2012, 11:14 AM
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