c.getLong（c.getColumnIndex（＆＃34; _id＆＃34;））总是返回0

Question

单击listview项目时尝试更新数据库

正确获取其他字段，但_id始终返回0

int Column1 = c.getColumnIndex（＆＃34; DESC＆＃34;）;   int Column2 = c.getColumnIndex（＆＃34; AMOUNT＆＃34;）;

long id_ = c.getLong（c.getColumnIndex（＆＃34; _id＆＃34;））;

主：   String [] from = new String [] {＆＃34; _id＆＃34;，＆＃34; DESC＆＃34;，＆＃34; AMOUNT＆＃34;};         int [] to = new int [] {R.id.list_content1，R.id.list_content2，R.id.list_content1};         cursorAdapter =                 new SimpleCursorAdapter（getContext（），R.layout.my_list_item2，c，from，to）;