如何在ALV显示中输入列名

DATA: it_data TYPE TABLE OF <内表类型>,
      wa_data TYPE <内表类型>,
      it_fieldcat TYPE lvc_t_fcat,
      wa_fieldcat TYPE lvc_s_fcat,
      alv_grid TYPE REF TO cl_gui_alv_grid.

* 定义内表类型和结构体
TYPES: BEGIN OF ty_data,
         col1 TYPE c LENGTH 10,
         col2 TYPE i,
       END OF ty_data.

* 定义字段目录
wa_fieldcat-fieldname = 'COL1'.
wa_fieldcat-ref_table = 'IT_DATA'.
wa_fieldcat-ref_field = 'COL1'.
APPEND wa_fieldcat TO it_fieldcat.

wa_fieldcat-fieldname = 'COL2'.
wa_fieldcat-ref_table = 'IT_DATA'.
wa_fieldcat-ref_field = 'COL2'.
APPEND wa_fieldcat TO it_fieldcat.

* 从数据库中读取数据到内表
SELECT col1 col2
  INTO TABLE it_data
  FROM <数据库表>.

* 创建ALV对象
CREATE OBJECT alv_grid
  EXPORTING
    i_parent = cl_gui_container=>screen0.

* 设置字段目录
CALL METHOD alv_grid->set_table_for_first_display
  EXPORTING
    is_layout      = VALUE lvc_s_layo( grid_title = 'ALV显示' )
  CHANGING
    it_outtab      = it_data
    it_fieldcatalog = it_fieldcat.