Question

我创建一个Android应用程序，在该应用程序中我插入和删除正常但我无法更新它。我试图更新，但我收到了一个错误。

public Helper(Context ctx) 
{
    this.context = ctx;
    DBHelper = new DatabaseHelper(context);
}

private static class DatabaseHelper extends SQLiteOpenHelper 
{
    DatabaseHelper(Context context) 
    {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) 
    {
        db.execSQL(DATABASE_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, 
    int newVersion) 
    {
        Log.w(TAG, "Upgrading database from version " + oldVersion 
                + " to "
                + newVersion + ", which will destroy all old data");
        db.execSQL("DROP TABLE IF EXISTS titles");
        onCreate(db);
    }
}    

//---opens the database---
public Helper open() throws SQLException 
{
    db = DBHelper.getWritableDatabase();
    return this;
}

//---closes the database---    
public void close() 
{
    DBHelper.close();
}

//---insert a title into the database---
public long insert(String name) 
{
     ContentValues initialValues = new ContentValues();
     initialValues.put("Name", name);
    return db.insert(DATABASE_TABLE, null,initialValues);
}
//---updates a title---
public long update(String name)
        {
            ContentValues args = new ContentValues();
            args.put("Name",name);

            return db.update(DATABASE_TABLE, args, 
                             "Name" + "=" + name, null);
        }


//---deletes a particular title---
public int delete(String name) 
{
   // return db.delete(DATABASE_TABLE,"Name="+name, null);
    return db.delete(DATABASE_TABLE,"Name=?",new String[]{String.valueOf(name)});
}

}

我的活动档案

    private static final String DATABASE_CREATE =
    "create table titles (_id integer primary key autoincrement, "
     + "Name text not null);";

private final Context context; 

private DatabaseHelper DBHelper;
private SQLiteDatabase db;

public Helper(Context ctx) 
{
    this.context = ctx;
    DBHelper = new DatabaseHelper(context);
}

private static class DatabaseHelper extends SQLiteOpenHelper 
{
    DatabaseHelper(Context context) 
    {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) 
    {
        db.execSQL(DATABASE_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, 
    int newVersion) 
    {
        Log.w(TAG, "Upgrading database from version " + oldVersion 
                + " to "
                + newVersion + ", which will destroy all old data");
        db.execSQL("DROP TABLE IF EXISTS titles");
        onCreate(db);
    }
}    

//---opens the database---
public Helper open() throws SQLException 
{
    db = DBHelper.getWritableDatabase();
    return this;
}

//---closes the database---    
public void close() 
{
    DBHelper.close();
}

//---insert a title into the database---
public long insert(String name) 
{
     ContentValues initialValues = new ContentValues();
     initialValues.put("Name", name);
    return db.insert(DATABASE_TABLE, null,initialValues);
}
//---updates a title---
public long update(String name)
        {
            ContentValues args = new ContentValues();
            args.put("Name",name);

            return db.update(DATABASE_TABLE, args, 
                             "Name" + "=" + name, null);
        }


//---deletes a particular title---
public int delete(String name) 
{
   // return db.delete(DATABASE_TABLE,"Name="+name, null);
    return db.delete(DATABASE_TABLE,"Name=?",new String[]{String.valueOf(name)});
}

}

Answer 1

在数据库中查询时，如果字段不是数字，那么你必须使用''来封闭文本。试试这个。

   return db.update(DATABASE_TABLE, args, 
                                 "Name" + "='" + name+"'", null);

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1 个答案: