java - 如何从数据库中获取 DISTINCT 值？

Question

我想以这种格式从数据库中获取值

1辆奥迪
3 尼桑

但我现在已经变成这样了。我不需要在输出中包含 _id。但我无法消除，因为当我删除它时它会抛出 NullPointerException。

id  MAKE
========= 
1   Audi  
2   Audi  
3   Nissan  
4   Audi

这是我用过的查询

cursor = db.rawQuery(
    "SELECT DISTINCT _id,MAKE FROM "+SQLiteAdapter.MYDATABASE_TABLE+
    " WHERE MAKE || ' ' || MODEL LIKE ?", new String[]{"%" + "" + "%"}
);

我是否需要完全更改序列以获得输出或对上述代码进行更改。谢谢。

我的代码

cursor = db.rawQuery("SELECT DISTINCT SERIES FROM "+SQLiteAdapter.MYDATABASE_TABLE+" WHERE YEAR=2012 AND MAKE='Audi' AND MODEL=?", new String[]{"A6"});

adapter = new SimpleCursorAdapter(this, R.layout.employee_list_item, cursor, new String[] {"series"}, new int[] {R.id.firstName});

employeeList.setAdapter(adapter);

Answer 1

尝试:

select min(id), min(make) from cars group by make