Question

I am importing records from Excel and I want to avoid duplicates. In ASP Classic I have written a function that checks the database for duplicates. If it finds one it adds a number on the end of the username and checks again if the username is unique, e.g petejones becomes petejones1. Unfortunately this script is soooooo slow as the data base has around 150k records and it takes forever to search for uniqueness. Is there a way to do the same directly in SQL Server 2008 in T-SQL? so the whole process will be wicked quick. Is there a make unique process?

Here is the function in classic ASP.. I know there are better ways to do this, so dont laugh at my scripting.

FUNCTION CreateUniqueUsername(str)
  SET DbConn = Server.CreateObject("ADODB.connection")
  DbConn.Open DSN_LINK
  nCounter = 0
  Unique = ""
  IF InStr(str, "@") > 0 THEN
     strUsername = Left(str,InStr(str, "@")-1)
  ELSE
     strUsername = str
  END IF
  strUsername = FormatUsername(strUsername)
  strSQL = "SELECT UserName FROM Member WHERE UserName = '" & strUsername & "';"
  SET rs = DbConn.Execute(strSQL)
  IF rs.EOF AND rs.BOF THEN
    nFinalUsername = strUsername
  ELSE
    DO UNTIL Unique = true
      nCounter = nCounter + 1
      nFinalUsername = strUsername & nCounter
      strSQL2 = "SELECT UserName FROM Member WHERE UserName = '" & nFinalUsername & " ' "
      SET objRS = DbConn.Execute(strSQL2)
      IF objRS.EOF THEN
        Unique = true
      ELSE
        intCount = intCount
      END IF
    LOOP
    objRS.Close
    SET objRS = Nothing 
  END IF
  rs.Close
  SET rs = Nothing 
  SET DbConn = Nothing
  CreateUniqueUsername = nFinalUsername
END FUNCTION

FUNCTION FormatUsername(str)
  Dim OutStr
  IF ISNULL(str) THEN EXIT FUNCTION
  OutStr = lCase(Trim(str))
  OutStr = Replace(OutStr, "’", "")
  OutStr = Replace(OutStr, "”", "")
  OutStr = Replace(OutStr, "'","")
  OutStr = Replace(OutStr, "&","and")
  OutStr = Replace(OutStr, "'", "")
  OutStr = Replace(OutStr, "*", "")
  OutStr = Replace(OutStr, ".", "")
  OutStr = Replace(OutStr, ",", "")
  OutStr = Replace(OutStr, CHR(34),"")
  OutStr = Replace(OutStr, " ","")
  OutStr = Replace(OutStr, "|","")
  OutStr = Replace(OutStr, "&","")
  OutStr = Replace(OutStr, "[","")
  OutStr = Replace(OutStr, ";", "")
  OutStr = Replace(OutStr, "]","")
  OutStr = Replace(OutStr, "(","")
  OutStr = Replace(OutStr, ")","")
  OutStr = Replace(OutStr, "{","")
  OutStr = Replace(OutStr, "}","")
  OutStr = Replace(OutStr, ":","")
  OutStr = Replace(OutStr, "/","")
  OutStr = Replace(OutStr, "\","")
  OutStr = Replace(OutStr, "?","")
  OutStr = Replace(OutStr, "@","")
  OutStr = Replace(OutStr, "!","")
  OutStr = Replace(OutStr, "_","")
  OutStr = Replace(OutStr, "''","")
  OutStr = Replace(OutStr, "%","")
  OutStr = Replace(OutStr, "#","")
  FormatUsername = OutStr
END FUNCTION

Any assistance would be greatly appreciated as I am still learning SQL.

Answer 1

You could do this in SQL.
This looks for a matching name. If a match is found, then it gets the maximum number currently appended to it and adds one. So at most it does two SELECTS. Should be faster when there are lots of duplicates.

-- example table
declare @Member table(ID int identity, UserName varchar(80))
insert @Member values('Pete')
insert @Member values('Jill')
insert @Member values('Bob')
insert @Member values('Sam')
insert @Member values('Pete1')
insert @Member values('Pete2')
insert @Member values('Pete3')
insert @Member values('Bob1')


declare @UserName varchar(80), @FinalUserName varchar(80)
set @UserName = 'Pete'

set @FinalUserName = @UserName
if(exists(SELECT 1 FROM @Member WHERE left(UserName,len(@UserName)) = @UserName))
begin
    SELECT 
        @FinalUserName = @UserName + convert(varchar(12),max(substring(UserName,len(@UserName)+1,99)+1)) 
    FROM @Member 
    WHERE left(UserName,len(@UserName)) = @UserName
end

SELECT @FinalUserName