经常有用户出现ALV导出是选择了默认导出方式，导致过后没法选择其他格式的导出。
解决：
REPORT Z_ALV_EXCEL.
tables:USR02.
selection-screen begin of block b2 with frame title t1 .
parameters:p_user like USR02-BNAME.
selection-screen end of block b2.
*程序初始化
INITIALIZATION.
t1 = '查询条件'.
START-OF-SELECTION.
DELETE FROM SALV_BS_ADMIN
WHERE OBJECT = 'GUI_ALV_XML_VER'
AND M_USER like p_user.
