如何在Android SQLite Open Helper中创建数据库？

问题描述 投票：0回答：1

我尝试过 sqlite 数据库表无法获取 

notification
表。我没有显示通知表 SQLite 数据库。我不知道我在哪里做错了。如果您知道错误，请告诉我。图片点击显示-> 

public class DbHandler extends SQLiteOpenHelper {

private static final int DATABASE_VERSION = 1;
private static final String DATABASE_NAME = "db_recipes_favorite";
private static final String TABLE_NAME = "tbl_recipes_favorite";

private static final String TABLE_NOTIFICATION = "notification";
private static final String KEY_ID = "id";
private static final String KEY_CAT_NAME = "category_name";
private static final String KEY_RECIPE_ID = "recipe_id";
private static final String KEY_RECIPE_TITLE = "recipes_title";
private static final String KEY_RECIPE_TIME = "recipe_time";
private static final String KEY_RECIPE_IMAGE = "recipe_image";
private static final String KEY_RECIPE_DESCRIPTION = "recipe_description";
private static final String KEY_VIDEO_URL = "video_url";
private static final String KEY_VIDEO_ID = "video_id";
private static final String KEY_CONTENT_TYPE = "content_type";
private static final String KEY_FEATURED = "featured";
private static final String KEY_TAGS = "tags";
private static final String KEY_TOTAL_VIEWS = "total_views";

private static final String unique_id = "unique_id";
private static final String title = "title";
private static final String message = "message";
private static final String big_image = "big_image";
private static final String link = "link";
private static final String post_id = "post_id";
public DbHandler(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
    String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_NAME + "("
            + KEY_ID + " INTEGER PRIMARY KEY,"
            + KEY_CAT_NAME + " TEXT,"
            + KEY_RECIPE_ID + " TEXT,"
            + KEY_RECIPE_TITLE + " TEXT,"
            + KEY_RECIPE_TIME + " TEXT,"
            + KEY_RECIPE_IMAGE + " TEXT,"
            + KEY_RECIPE_DESCRIPTION + " TEXT,"
            + KEY_VIDEO_URL + " TEXT,"
            + KEY_VIDEO_ID + " TEXT,"
            + KEY_CONTENT_TYPE + " TEXT,"
            + KEY_FEATURED + " TEXT,"
            + KEY_TAGS + " TEXT,"
            + KEY_TOTAL_VIEWS + " TEXT"
            + ")";

    db.execSQL(CREATE_CONTACTS_TABLE);

    String CREATE_CONTACTS_NOTIFICATION = "CREATE TABLE " + TABLE_NOTIFICATION + "("
            + unique_id + " INTEGER PRIMARY KEY,"
            + title + " TEXT,"
            + message + " TEXT,"
            + big_image + " TEXT,"
            + link + " TEXT,"
            + post_id + " TEXT"
            + ")";


    db.execSQL(CREATE_CONTACTS_NOTIFICATION);

}



// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
    // Drop older table if existed
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);

    // Create tables again
    onCreate(db);


    db.execSQL("DROP TABLE IF EXISTS " + TABLE_NOTIFICATION);

    // Create tables again
    onCreate(db);
}

//Adding Record in Database

public void AddtoFavorite(Recipe p) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(KEY_CAT_NAME, p.getCategory_name());
    values.put(KEY_RECIPE_ID, p.getRecipe_id());
    values.put(KEY_RECIPE_TITLE, p.getRecipe_title());
    values.put(KEY_RECIPE_TIME, p.getRecipe_time());
    values.put(KEY_RECIPE_IMAGE, p.getRecipe_image());
    values.put(KEY_RECIPE_DESCRIPTION, p.getRecipe_description());
    values.put(KEY_VIDEO_URL, p.getVideo_url());
    values.put(KEY_VIDEO_ID, p.getVideo_id());
    values.put(KEY_CONTENT_TYPE, p.getContent_type());
    values.put(KEY_FEATURED, p.getFeatured());
    values.put(KEY_TAGS, p.getTags());
    values.put(KEY_TOTAL_VIEWS, p.getTotal_views());

    // Inserting Row
    db.insert(TABLE_NAME, null, values);
    db.close(); // Closing database connection

}

// Getting All Data
public List<Recipe> getAllData() {
    List<Recipe> dataList = new ArrayList<Recipe>();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + TABLE_NAME + " ORDER BY id DESC";

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            Recipe values = new Recipe();
            values.setId(Integer.parseInt(cursor.getString(0)));
            values.setCategory_name(cursor.getString(1));
            values.setRecipe_id(cursor.getString(2));
            values.setRecipe_title(cursor.getString(3));
            values.setRecipe_time(cursor.getString(4));
            values.setRecipe_image(cursor.getString(5));
            values.setRecipe_description(cursor.getString(6));
            values.setVideo_url(cursor.getString(7));
            values.setVideo_id(cursor.getString(8));
            values.setContent_type(cursor.getString(9));
            values.setFeatured(cursor.getString(10));
            values.setTags(cursor.getString(11));
            values.setTotal_views(cursor.getLong(12));
            // Adding contact to list
            dataList.add(values);
        } while (cursor.moveToNext());
    }

    // return contact list
    return dataList;
}

//getting single row
public List<Recipe> getFavRow(String id) {
    List<Recipe> dataList = new ArrayList<Recipe>();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + TABLE_NAME + " WHERE recipe_id=" + id;

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            Recipe values = new Recipe();
            values.setId(Integer.parseInt(cursor.getString(0)));
            values.setCategory_name(cursor.getString(1));
            values.setRecipe_id(cursor.getString(2));
            values.setRecipe_title(cursor.getString(3));
            values.setRecipe_time(cursor.getString(4));
            values.setRecipe_image(cursor.getString(5));
            values.setRecipe_description(cursor.getString(6));
            values.setVideo_url(cursor.getString(7));
            values.setVideo_id(cursor.getString(8));
            values.setContent_type(cursor.getString(9));
            values.setFeatured(cursor.getString(10));
            values.setTags(cursor.getString(11));
            values.setTotal_views(cursor.getLong(12));
            // Adding contact to list
            dataList.add(values);
        } while (cursor.moveToNext());
    }

    // return contact list
    return dataList;
}

//for remove favorite
public void RemoveFav(Recipe contact) {
    SQLiteDatabase db = this.getWritableDatabase();
    db.delete(TABLE_NAME, KEY_RECIPE_ID + " = ?",
            new String[]{String.valueOf(contact.getRecipe_id())});
    db.close();
}

public void notifcation(long unique_id, String title, String message, String big_image, String link, long post_id) {

    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put("unique_id", unique_id);
    values.put("title", title);
    values.put("message", message);
    values.put("big_image", big_image);
    values.put("link", link);
    values.put("post_id", post_id);


    // Inserting Row
    db.insert(TABLE_NOTIFICATION, null, values);
    db.close(); // Closing database connection




}

public enum DatabaseManager {
    INSTANCE;
    private SQLiteDatabase db;
    private boolean isDbClosed = true;
    DbHandler dbHelper;

    public void init(Context context) {
        dbHelper = new DbHandler(context);
        if (isDbClosed) {
            isDbClosed = false;
            this.db = dbHelper.getWritableDatabase();
        }

    }

    public boolean isDatabaseClosed() {
        return isDbClosed;
    }

    public void closeDatabase() {
        if (!isDbClosed && db != null) {
            isDbClosed = true;
            db.close();
            dbHelper.close();
        }
    }
}

}

android sqlite
1个回答
0
投票

在

onCreate()
中添加通知表创建之前，您是否运行过应用程序？

开发数据库应用程序时的一个常见问题是，如果您增量添加表，但不更新数据库版本，则 

onCreate()
不会再次运行，
onUpgrade()
也不会。

要测试该理论，请将 

DATABASE_VERSION
更改为 
2
并重新运行。如果这是问题所在，您应该创建该表。请注意，您的 
onCreate()
函数中有两次 
onUpgrade()
运行 - 第二次可能会失败，因为 
tbl_recipes_favorite
已经存在 - 我建议删除第一个表。

如果有效，请将您的 

DATABASE_VERSION
更改回 
1
。我还建议卸载该应用程序，然后再次运行。

请注意，您也可以在添加新表时卸载，下次运行将从头开始创建数据库。

仅供参考 - 您可能想研究一下 Room - 它确实简化了数据库管理。您所拥有的一切都可以发挥作用，但需要维护的工作还有很多。 Room 还会在未更新版本的情况下警告您数据库已更改。

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