Question

如何调用此方法将字符串作为参数或如何执行此查询？

代码：

public class Samsung extends ListActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_samsung);        
        Intent intent = getIntent();       
        ArrayList<HashMap<String, String>> SamsungList = getSamsungInfo(null);
        ListAdapter adapter = new SimpleAdapter(Samsung.this, SamsungList, R.layout.samsung_list, new String[] {Sqlite.COLUMN_MNAME, Sqlite.COLUMN_MMODEL,
                             Sqlite.COLUMN_MPRICE,Sqlite.COLUMN_MCAMERA} , new int[] {R.id.nameofsamsung, R.id.modelofsamsung, R.id.priceofsamsung, R.id.cameraofsamsung});
        setListAdapter(adapter);
    }  

public ArrayList <HashMap<String, String>> getSamsungInfo(String samsung) { 
    ArrayList <HashMap<String, String>> wordList;
    wordList= new ArrayList <HashMap<String, String>>();
    Sqlite sqlll = new Sqlite(this);
    SQLiteDatabase database = sqlll.getReadableDatabase();
    String selectQuery = "SELECT * FROM mobile WHERE mname="+samsung+"'";
    Cursor cursor = database.rawQuery(selectQuery, null);
    if (cursor.moveToFirst()) {
        do {
                HashMap<String, String> map = new HashMap<String, String>();
                map.put(Sqlite.COLUMN_MNAME, cursor.getString(0));
                map.put(Sqlite.COLUMN_MMODEL, cursor.getString(1));
                map.put(Sqlite.COLUMN_MPRICE, cursor.getString(2));
                map.put(Sqlite.COLUMN_MCAMERA, cursor.getString(3));
                wordList. add(map);                                
        } while (cursor.moveToNext());
    }                  
return wordList ;
}  
}

给我一个错误，就是没有名为＆＃34; null＆＃34;的列。那么在调用方法时我应该通过什么呢。它没有采取三星，它是移动列mname中的插入值。

Answer 1

您需要在SQL中引用您的文字：

String selectQuery = "SELECT * FROM mobile WHERE mname='"+samsung+"'";

虽然最好使用bind args，如下所示：

String selectQuery = "SELECT * FROM mobile WHERE mname=?";
Cursor cursor = database.rawQuery(selectQuery, new String[] { samsung });

另外，将实际参数传递给getSamsungInfo()而不是null。

Answer 2

语法错误：

String selectQuery = "SELECT * FROM mobile WHERE mname="+samsung+"'";

它应该是（正确的撇号来包围字符串值）：

String selectQuery = "SELECT * FROM mobile WHERE mname = 'samsung'";

OR，更好（这里我使用变量），

String selectQuery = "SELECT * FROM mobile WHERE mname = '" + mobileName + "'";

其中mobileName是一个传递的字符串，其中包含（例如）＆＃34; samsung＆＃34;

OR，甚至更好（绑定参数），

String selectQuery = "SELECT * FROM mobile WHERE mname = ?";

接下来是：

Cursor cursor = database.rawQuery(selectQuery, new String[] {mobileName});

其中mobileName是一个传递的字符串，其中包含（例如）＆＃34; samsung＆＃34; - 与之前相同这里null被字符串参数

取代

如何在SQLite中创建where子句查询？

2 个答案: