simple_select:
SELECT ... target_list...
{
...
n->targetList =$3;
...
}
修改为：
simple_select:
SELECT ... target_list...
{
...
n->targetList =$3;
...
if ( n->targetList->head->data.ptr_value == NULL)
fprintf(stderr,"ptr_value is NULL);
else
fprintf(stderr,"ptr_values is not NULL);
}
可以编译通过。运行中显示 "ptr_value is NULL"