Question

我正在尝试使用自定义cursorAdapter提供listview。

我收到此错误：03-16 03:25:39.968: E/AndroidRuntime(14552): Caused by: android.database.sqlite.SQLiteException: no such column: _id: , while compiling: SELECT _id, content_note FROM notes 在这一行values.put(DataBaseHelper.DATABASEBASE_CONTENT_NOTE, note.getContent());

以下是我的2个连接类

    package com.android.database;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DataBaseHelper extends SQLiteOpenHelper{

    private static final String DATABASE_NAME = "db";
    public static final String DATABASE_TABLE_NOTE = "notes";
    public static final String DATABASE_ID_NOTE = "_id";
    public static final String DATABASE_CONTENT_NOTE = "content_note";

    public DataBaseHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + DATABASE_TABLE_NOTE + " (" + DATABASE_ID_NOTE + " INTEGER PRIMARY KEY, " + DATABASE_CONTENT_NOTE + " TEXT);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        android.util.Log.w("Constants", "Maj de la base, suppression de toutes les anciennes donnees");
        db.execSQL("DROP TABLE IF EXISTS Notes");
        onCreate(db);
    }

}



    package com.android.database;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;

public class NoteDataSource{

    private SQLiteDatabase database;
    private DataBaseHelper dbHelper;
    private String[] allColumns = { DataBaseHelper.DATABASE_ID_NOTE,
            DataBaseHelper.DATABASE_CONTENT_NOTE };

    public NoteDataSource(Context context) {
        dbHelper = new DataBaseHelper(context);
    }


    public void open() throws SQLException {
        database = dbHelper.getWritableDatabase();
    }

    public void close() {
        dbHelper.close();
    }

    public Cursor createNoteTop(String note) {

        //recuperer le bon id

//      int idNote = getFirstId().getId();
        int idNote = 1 ;

        ContentValues values = new ContentValues();
        values.put(DataBaseHelper.DATABASE_ID_NOTE, idNote);
        values.put(DataBaseHelper.DATABASE_CONTENT_NOTE, note);
        long insertId = database.insert(DataBaseHelper.DATABASE_TABLE_NOTE, null,
                values);
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, DataBaseHelper.DATABASE_ID_NOTE + " = " + insertId, null,
                null, null, null);
        cursor.moveToFirst();
        return cursor;
    }

    public Cursor createNoteBottom(String note) {

        //recuperer le bon id

        int idNote = getLastId().getId();

        ContentValues values = new ContentValues();
        values.put(DataBaseHelper.DATABASE_ID_NOTE, idNote);
        values.put(DataBaseHelper.DATABASE_CONTENT_NOTE, note);
        long insertId = database.insert(DataBaseHelper.DATABASE_TABLE_NOTE, null,
                values);
        // To show how to query
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, DataBaseHelper.DATABASE_ID_NOTE + " = " + insertId, null,
                null, null, null);
        cursor.moveToFirst();
        return cursor;
    }

    public void deleteNote(Note note) {
        long id = note.getId();
        System.out.println("Note deleted with id: " + id);
        database.delete(DataBaseHelper.DATABASE_TABLE_NOTE, DataBaseHelper.DATABASE_ID_NOTE
                + " = " + id, null);
    }

    public Cursor getAllNotes() {
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, null, null, null, null, null);
        return cursor;
    }

    private Note getFirstId(){
        Note notes = new Note();
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, null, null, null, null, null);
        cursor.moveToFirst();
        notes = cursorToNote(cursor);

        return notes;

    }

    private Note getLastId(){

        Note notes = new Note();
        Cursor cursor = database.query(DataBaseHelper.DATABASE_TABLE_NOTE,
                allColumns, null, null, null, null, null);
        cursor.moveToLast();
        notes = cursorToNote(cursor);

        return notes;

    }

    private Note cursorToNote(Cursor cursor) {
        Note note = new Note();
        note.setId(cursor.getInt(0));
        note.setContent(cursor.getString(1));
        return note;
    }




}

这必须简单，并且来自我已经使用其他名称字段创建基础并且不升级的事实。

感谢。

Answer 1

这必须简单，并且来自我已经使用其他名称字段创建基础并且不升级的事实。

我猜你是对的。您应该在更改数据库时增加版本号。然后，您可以将代码置于可以处理转换的onUpgrade中。

private static final int DATABASE_VERSION = 2;
public DataBaseHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

onUpgrade的架构通常就是这样

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // it all started this way
    if (oldVersion < 1) {
        db.execSQL("CREATE TABLE supertable...");
    }

    // in version 2 I decided that I need another table
    if (oldVersion < 2) {
        db.execSQL("CREATE TABLE cooltable...");
    }

    // in version 3 I decided that the table is not required anymore
    if (oldVersion < 3) {
        db.execSQL("DROP TABLE cooltable...");
    }
    // remember to increase DATABASE_VERSION if you add steps here.
}

该升级架构还允许安装了您的应用的用户将应用升级到新版本，而不会损坏数据库。

Answer 2

您应确保_id字段还具有AUTOINCREMENT属性。

我认为你也可以完全放弃它，它会自动为你自动添加。

有一个通用的概述here。

android没有这样的列：_id

2 个答案: