Question

我是SQLite数据库和Android应用程序的新手。我想在用户输入名称并单击“删除帐户”按钮时删除特定记录。

我有以下代码，但我似乎无法实现我想要的。您对我的代码可能出现的问题有任何见解吗？

在mydbadapter.java

中

    private static final String DATABASE_NAME = "customer.db";
    private static final String DATABASE_TABLE = "customerAcc";
    private static final int DATABASE_VERSION = 1;
    private SQLiteDatabase _db;
    private final Context context;

    public static final String name = "_name";
    public static final int COLUMN_NAME_ID = 0;
    public static final String password = "_password";
    public static final int COLUMN_PW_ID = 1;
    public static final String address = "_address";
    public static final int COLUMN_ADDRESS_ID = 2;
    public static final String phoneNumber = "_phoneNumber";
    public static final int COLUMN_PHONE_ID = 3;


    protected static final String DATABASE_CREATE = "create table " + DATABASE_TABLE + " " + "(" + name + " Text not null, " + password + " Text not null, "
            + address + " Text not null, " + phoneNumber + " text not null);";

    private String MYDBADAPTER_LOG_CAT = "MY_LOG";

    private MyDBOpenHelper dbHelper;

    public MyDbAdapter(Context _context)
    {
        this.context = _context;

        dbHelper = new MyDBOpenHelper (context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    public void close()
    {
        _db.close();
        Log.w(MYDBADAPTER_LOG_CAT, "DB Closed");
    }

    public void open() throws SQLiteException
    {
        try
        {
            _db = dbHelper.getWritableDatabase();
            Log.w(MYDBADAPTER_LOG_CAT, "DB opened as writable database");
        }
        catch (SQLiteException e)
        {
            _db = dbHelper.getReadableDatabase();
            Log.w(MYDBADAPTER_LOG_CAT, "DB opened as readable database");
        }
    }

    public long insertEntry(String cname, String cpassword, String caddress, String cphone)
    {   
        // create codes go here
    }

    public boolean removeEntry(String custname)
    {
        try
        {
        _db = dbHelper.getWritableDatabase();

        return _db.delete(DATABASE_TABLE, name + "=" + custname, null)>0;
        }
        catch (SQLiteException e)
        {
            return false;
        }
    }

    public boolean updateEntry(long _rowIndex, String entryName, String entryTel)
    {
        //update codes are here
    }

    public Cursor retrieveAllEntriesCursor()
    {
        //retrieve codes are here
    }

    public class MyDBOpenHelper extends SQLiteOpenHelper
    {
        public MyDBOpenHelper(Context context, String name, CursorFactory factory, int version)
        {
            super(context, name, factory, version);
            // TODO Auto-generated constructor stub
        }

        @Override
        public void onCreate(SQLiteDatabase db)
        {
            // TODO Auto-generated method stub
            db.execSQL(DATABASE_CREATE);
            Log.w(MYDBADAPTER_LOG_CAT, "Helper : DB " + DATABASE_TABLE + " Created!!");
        }


    } // End of myDBOpenHelper

}// End of myDBAdapter

在MainActivity.java

中

btnRemove.setOnClickListener(new OnClickListener()
    {

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            String custname = etRName.getText().toString();

            myDB.removeEntry(custname);
        }       
    });

我的代码没有给我任何错误，但是当我点击“删除帐户”按钮时，记录仍然存在。

Answer 1

虽然我会推荐

，但是有效

db.delete(TABLE, "column_name=?", new String[] { String.valueOf(custname) });

或使用

String query = "DELETE FROM " +TABLE_NAME+ " WHERE "  + COLUM_NAME+ " = " + "'"+VALUE +"'" ;
db.execSQL(query);

Answer 2

public boolean removeEntry（String custname） {

bolean returnBoolean;

试 {

 db.delete(TABLE_NAME, "column_name=?", new String[]{String.valueOf(custname)});
 returnBoolean= true;

}

catch(Exception e)
{
    returnBoolean= false;
    e.printStackTrace();
}

finally
{
    db.close();
}

return returnBoolean; }

Answer 3

您的查询语法似乎有些问题。这是我的代码中的一行，它适用于我

db.delete(Table_name, KEY_COLUMN + "=?", new String[] {String.valueOf(custname)});

你没有获得查询结构。第二个参数用于查询的 where 子句。请参阅THIS帖子的第一个答案，以便更好地理解语法。

Answer 4

我建议你看看cupboard，这里的代码会大大减少/简化，这使得这种工作更具可读性/可理解性：）

在SQLite Android中从数据库中删除行

4 个答案: