ODBC访问MYSQL内存泄露 - VC/MFC / 基础类

我通过ODBC访问MYSQL,但是每次执行都会增大100K左右，要1次两次也就无所谓了，但是关键是1秒执行2-3次，执行1天想想都感到心寒了，谁能帮忙看下哪儿泄露的，怎么改法



C/C++ code:

#define LOGIN_TIMEOUT 30
#define MAXBUFLEN 255
//global
SQLHENV henv = NULL;
SQLHDBC hdbc = NULL;
SQLHSTMT hstmt = NULL;
SQLRETURN result;




void DBConnect(HWND hwnd)
{
SQLCHAR ConnStrIn[MAXBUFLEN] = "DRIVER={MySQL ODBC 5.1 Driver};SERVER=127.0.0.1;UID=root;PWD=;DATABASE=test;CharSet=gbk;";
SQLCHAR ConnStrOut[MAXBUFLEN];
result = SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &henv);
result = SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (void*)SQL_OV_ODBC3, 0);
result = SQLAllocHandle(SQL_HANDLE_DBC, henv, &hdbc);
result = SQLSetConnectAttr(hdbc, SQL_LOGIN_TIMEOUT, (void*)LOGIN_TIMEOUT, 0);
result = SQLDriverConnect(hdbc,NULL,
ConnStrIn,SQL_NTS,
ConnStrOut,MAXBUFLEN,
(SQLSMALLINT *)0,SQL_DRIVER_NOPROMPT);
if(SQL_ERROR==result)
{
PostQuitMessage(0);
return;
}
}

void DBDisconnect(HWND hwnd)
{
SQLFreeStmt(hstmt,SQL_CLOSE);
SQLDisconnect(hdbc);
SQLFreeHandle(SQL_HANDLE_DBC,hdbc);
SQLFreeHandle(SQL_HANDLE_ENV,henv);
}

void DoNotSelectJob(HWND hwnd)
{
TCHAR buff[256];
ZeroMemory(buff,sizeof(buff)/sizeof(TCHAR));