十万火急？咋搞的inparam/outparam???????

[mdh690928]

为什么在如下语句，之后outparm任为NULL????????????
retcode = SQLExecute(hstmt);

开发工具：VC++
数据库：Sybase 11.9

存储过程：
CREATE PROCEDURE dbo.proc_test1
inparm varchar(20),
outparm varchar(30)
AS
BEGIN
select @outparm = @inparm + "12"
return 999
END

程序代码：

......

SQLCHAR inparm[20];
SQLCHAR outparm[30];
short ret=0;
SQLINTEGER m_vcbValues[10];
SQLINTEGER ptr=0;

ZeroMemory(inparm, 20);
ZeroMemory(outparm, 30);

strcpy(inparm, "abc");

......

retcode = SQLPrepare(hstmt, (SQLCHAR *)"{？=call proc_test1(?,?)}", SQL_NTS);

retcode = SQLBindParameter(hstmt, 1, SQL_PARAM_OUTPUT, SQL_C_SSHORT,
SQL_INTEGER, 0, 0, &ret, 0, m_vcbValue+ptr++);

retcode = SQLBindParameter(hstmt, 2, SQL_PARAM_INPUT, SQL_C_CHAR,
SQL_CHAR, 20, 0, inparm, 20, m_vcbValue+ptr++);

retcode = SQLBindParameter(hstmt, 3, SQL_PARAM_OUTPUT, SQL_C_CHAR,
SQL_CHAR, 30, 0, outparm, 30, m_vcbValue+ptr++);

retcode = SQLExecute(hstmt);

printf("%s\n", outparm);

......

[ZHENG017]

alter procedure proc_test1(@input varchar(20),@outparm varchar(30) output)//注意要加output属性
as
begin
select @outparm=@input+'123'
return 999
end