Converter Function Postgres em Mysql

Infraestrutura Banco de Dados
, ,
#1

Olá, estou tentando converter essa função postgres em Mysql

CREATE OR REPLACE FUNCTION dbsinan.decriptografanova(S character varying)
declare
  InputString varchar;
  OutputString varchar;
  CharConst varchar;
  x Integer;
  i Integer;
  z Integer;

Begin
  CharConst = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
  InputString = S;
  OutputString = '';
  z = Length(InputString);

  If z > 0 then
    For i in 1..z Loop
      x = strpos(CharConst,substr(InputString,i,1));
      If x > 0 then
        OutputString = OutputString||dbsinan.getChar(x - i - z);
	/*
	OutputString = OutputString||dbsinan.getChar(x + i + z);
	Para codificar usa a soma, para decodificar usa a subtracao
	*/
      Else
        OutputString = OutputString||substr(InputString,i,1);
      End If;
    End Loop;
    return OutputString;
  Else
    return OutputString;
  End If;
End;

Valeu