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convert this usp to t-sql function

Posted on 2009-07-02
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Last Modified: 2012-06-21
can someone convert this stored procedure into a function?

usage: exec dbo.GenerateRandomString 1,1,0,null,5,@a OUT

the function needs to be able to be used in a default value field in a sql server table..
/***************************************************************************
* Created By: Raymond Lewallen
* Date:  05/16/2005
* Purpose: Generate a random string of given length
*
* Comments: Everything is self-explanatory.  Right now
*  max length is set to 100. So anything between 1
*  and 100 will work for a length.
*
*   If you specify a @charactersToUse,
*  the bit flags get ignored.
*
*   All spaces are stripped from the 
*  @charactersToUse.
*
*   Characters can repeat. Will be 
*  handled in a future version.
*  http://codebetter.com/blogs/raymond.lewallen/archive/2005/05/17/63281.aspx
***************************************************************************/
CREATE procedure dbo.GenerateRandomString (
 @useNumbers bit,
 @useLowerCase bit,
 @useUpperCase bit,
 @charactersToUse as varchar(100),
 @passwordLength as smallint,
 @password varchar(100) OUT
)
As
Begin
 
if @passwordLength <= 0
 raiserror('Cannot generate a random string of zero length.',16,1)
 
declare @characters varchar(100)
declare @count int
 
set @characters = ''
 
if @useNumbers = 1
begin
 -- load up numbers 0 - 9
 set @count = 48
 while @count <=57
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
if @useLowerCase = 1
begin
 -- load up uppercase letters A - Z
 set @count = 65
 while @count <=90
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
if @useUpperCase = 1
begin
 -- load up lowercase letters a - z
 set @count = 97
 while @count <=122
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
set @count = 0
set @password = ''
 
-- If you specify a character set to use, the bit flags get ignored.
if Len(@charactersToUse) > 0
begin
 while charindex(@charactersToUse,' ') > 0
 begin
  set @charactersToUse = replace(@charactersToUse,' ','')
 end
 
 if Len(@charactersToUse) = 0
  raiserror('Cannot use an empty character set.',16,1)
 
 while @count <= @passwordLength
 begin
     set @password = @password + SUBSTRING(@charactersToUse,CAST(ABS(CHECKSUM(NEWID()))*RAND(@count) as int)%LEN(@charactersToUse)+1,1)
     set @count = @count + 1
 end
end
else
begin
 while @count <= @passwordLength
 begin
     set @password = @password + SUBSTRING(@characters,CAST(ABS(CHECKSUM(NEWID()))*RAND(@count) as int)%LEN(@characters)+1,1)
     set @count = @count + 1
 end
end
set @password = 'bR' + @password
end
 
GO

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Question by:conrad2010
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10 Comments
 
LVL 59

Accepted Solution

by:
Kevin Cross earned 250 total points
ID: 24767709

/***************************************************************************
* Created By: Raymond Lewallen
* Date:  05/16/2005
* Purpose: Generate a random string of given length
*
* Comments: Everything is self-explanatory.  Right now
*  max length is set to 100. So anything between 1
*  and 100 will work for a length.
*
*   If you specify a @charactersToUse,
*  the bit flags get ignored.
*
*   All spaces are stripped from the 
*  @charactersToUse.
*
*   Characters can repeat. Will be 
*  handled in a future version.
*  http://codebetter.com/blogs/raymond.lewallen/archive/2005/05/17/63281.aspx
***************************************************************************/
CREATE FUNCTION dbo.GenerateRandomString (
 @useNumbers bit,
 @useLowerCase bit,
 @useUpperCase bit,
 @charactersToUse as varchar(100),
 @passwordLength as smallint
)
RETURNS varchar(100)
As
Begin
DECLARE @password varchar(100);
 
if @passwordLength <= 0
 raiserror('Cannot generate a random string of zero length.',16,1)
 
declare @characters varchar(100)
declare @count int
 
set @characters = ''
 
if @useNumbers = 1
begin
 -- load up numbers 0 - 9
 set @count = 48
 while @count <=57
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
if @useLowerCase = 1
begin
 -- load up uppercase letters A - Z
 set @count = 65
 while @count <=90
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
if @useUpperCase = 1
begin
 -- load up lowercase letters a - z
 set @count = 97
 while @count <=122
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
set @count = 0
set @password = ''
 
-- If you specify a character set to use, the bit flags get ignored.
if Len(@charactersToUse) > 0
begin
 while charindex(@charactersToUse,' ') > 0
 begin
  set @charactersToUse = replace(@charactersToUse,' ','')
 end
 
 if Len(@charactersToUse) = 0
  raiserror('Cannot use an empty character set.',16,1)
 
 while @count <= @passwordLength
 begin
     set @password = @password + SUBSTRING(@charactersToUse,CAST(ABS(CHECKSUM(NEWID()))*RAND(@count) as int)%LEN(@charactersToUse)+1,1)
     set @count = @count + 1
 end
end
else
begin
 while @count <= @passwordLength
 begin
     set @password = @password + SUBSTRING(@characters,CAST(ABS(CHECKSUM(NEWID()))*RAND(@count) as int)%LEN(@characters)+1,1)
     set @count = @count + 1
 end
end
set @password = 'bR' + @password
 
RETURN @password;
end
 
GO

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LVL 59

Expert Comment

by:Kevin Cross
ID: 24767719
As you see, just moved the out parameter to be the RETURN type along with supporting code to ensure it is returned at end of func.
0
 

Author Comment

by:conrad2010
ID: 24767749
checking...
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Author Comment

by:conrad2010
ID: 24767762
error: invalid use of newid within a function...
0
 
LVL 75

Assisted Solution

by:Aneesh Retnakaran
Aneesh Retnakaran earned 250 total points
ID: 24767828


drop view vw_NewID
GO
create view vw_NewID
as
select NEWID() as NewID
GO

create view vw_RandID
as
select RAND() as RandID
GO

CREATE FUNCTION dbo.GenerateRandomString (
 @useNumbers bit,
 @useLowerCase bit,
 @useUpperCase bit,
 @charactersToUse as varchar(100),
 @passwordLength as smallint
)
RETURNS varchar(100)
As
Begin
DECLARE @password varchar(100);
 
--if @passwordLength <= 0
-- raiserror('Cannot generate a random string of zero length.',16,1)
 
declare @characters varchar(100)
declare @count int
 
set @characters = ''
 
if @useNumbers = 1
begin
 -- load up numbers 0 - 9
 set @count = 48
 while @count <=57
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
if @useLowerCase = 1
begin
 -- load up uppercase letters A - Z
 set @count = 65
 while @count <=90
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
if @useUpperCase = 1
begin
 -- load up lowercase letters a - z
 set @count = 97
 while @count <=122
 begin
     set @characters = @characters + Cast(CHAR(@count) as char(1))
     set @count = @count + 1
 end
end
 
set @count = 0
set @password = ''
 
-- If you specify a character set to use, the bit flags get ignored.
if Len(@charactersToUse) > 0
begin
 while charindex(@charactersToUse,' ') > 0
 begin
  set @charactersToUse = replace(@charactersToUse,' ','')
 end
 
 --if Len(@charactersToUse) = 0
 -- raiserror('Cannot use an empty character set.',16,1)
 
 declare @newID uniqueidentifier
 declare @RandID numeric(10,8)
 
 while @count <= @passwordLength
 begin
       SELECT @newID = [NewID] from vw_NewID
       SELECT @RandID = RandID from vw_RandID       
     set @password = @password + SUBSTRING(@charactersToUse,CAST(ABS(CHECKSUM(@newID))*@RandID*(@count) as int)%LEN(@charactersToUse)+1,1)
     set @count = @count + 1
 end
end
else
begin
 while @count <= @passwordLength
 begin
       SELECT @newID = [NewID] from vw_NewID
       SELECT @RandID = RandID from vw_RandID       
 
     set @password = @password + SUBSTRING(@characters,CAST(ABS(CHECKSUM(@newID))*@RandID*(@count) as int)%LEN(@characters)+1,1)
     set @count = @count + 1
 end
end
set @password = 'bR' + @password
 
RETURN @password;
end
 
GO

--limitations,
you cannot use the RAISERROR within the function
0
 
LVL 59

Expert Comment

by:Kevin Cross
ID: 24767846
Sorry I should have looked better at the inner workings of the code.

RAND() and NEWID() won't be allowed:
http://www.dbtechie.com/sql-server/user-defined-functions-udf/random-thoughts-on-sql-server/
The linked article shows how to get around using a view.

The RAISEERROR lines will need to be changed as well.  Maybe return NULL at those points instead.
0
 

Author Comment

by:conrad2010
ID: 24767959
this seems to work, but I'm not able to set this function as a default value on a string field in SQL 2000...

SQL Server changes the default value to  N'fnGenerateRandomString()'

is it possible to use the output of a function automatically? something like getdate()...
0
 
LVL 75

Expert Comment

by:Aneesh Retnakaran
ID: 24768067
columnName  default dbo.functionName()

dont put quotes around the function
0
 

Author Comment

by:conrad2010
ID: 24768094
I'm using the SQL Server Enterprise Manager and each time I put the function name in the Default value, it's automatically changed to N'dbo.fnGenerateRandomString()' when I exit the field...
0
 
LVL 59

Expert Comment

by:Kevin Cross
ID: 24768254
It won't work through Enterprise Manager or SQL Management Studio at least as far as I know.  For existing column, you can do this though.
alter table your_table_name
add constraint df_password default (dbo.GenerateRandomString(1,1,0,null,5)) for your_column_name

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