这是我的第一篇文章！我希望你能帮助我！ ： - ）
我使用了开发人员文档中NotePadExample提供的代码来创建数据库。现在我想添加第二个表来存储不同的数据。我可以毫无问题地添加注释，并且注释表的创建方式与我的路由表类似。我只是“复制”并编辑了给定的代码，但当我尝试插入新表时，我收到一条错误说：
“0ERROR / Database（370）：android.database.sqlite.SQLiteException：没有这样的表：routes :,同时编译：INSERT INTO路由（行，到达，持续时间，开始）VALUES（？，？，？，？ ）;“
有人可以快速查看我的DbAdapter类，尤其是onCreate（）方法。并给我一个提示或解决方案？我真的没有看到任何问题。我的代码编译没有任何错误..
public class DbAdapter {
public static final String KEY_FROM = "title";
public static final String KEY_TO = "body";
public static final String KEY_ROWID = "_id";
public static final String KEY_START = "start";
public static final String KEY_ARRIVAL = "arrival";
public static final String KEY_LINE = "line";
public static final String KEY_DURATION = "duration";
private static final String DATABASE_NAME = "data";
private static final String DATABASE_NOTESTABLE = "notes";
private static final String DATABASE_ROUTESTABLE = "routes";
private static final String TAG = "DbAdapter";
private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;
/**
* Database creation sql statement
*/
private static final String DATABASE_CREATE_NOTES =
"create table notes (_id integer primary key autoincrement, "
+ "title text not null, body text not null)";
private static final String DATABASE_CREATE_ROUTES =
"create table routes (_id integer primary key autoincrement, "
+ "start , arrival , "
+ "line , duration );";
private static final int DATABASE_VERSION = 3;
private final Context mCtx;
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_NOTES);
Log.d(TAG, "created notes table");
db.execSQL(DATABASE_CREATE_ROUTES);
Log.d(TAG, "created routes table");
}
@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 notes");
db.execSQL("DROP TABLE IF EXISTS routes");
onCreate(db);
}
}
/**
* Constructor - takes the context to allow the database to be
* opened/created
*
* @param ctx the Context within which to work
*/
public DbAdapter(Context ctx) {
this.mCtx = ctx;
}
/**
* Open the notes database. If it cannot be opened, try to create a new
* instance of the database. If it cannot be created, throw an exception to
* signal the failure
*
* @return this (self reference, allowing this to be chained in an
* initialization call)
* @throws SQLException if the database could be neither opened or created
*/
public DbAdapter open() throws SQLException {
mDbHelper = new DatabaseHelper(mCtx);
mDb = mDbHelper.getWritableDatabase();
return this;
}
public void close() {
mDbHelper.close();
}
/**
* Create a new note using the title and body provided. If the note is
* successfully created return the new rowId for that note, otherwise return
* a -1 to indicate failure.
*
* @param title the title of the note
* @param body the body of the note
* @return rowId or -1 if failed
*/
public long createNote(String title, String body) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_FROM, title);
initialValues.put(KEY_TO, body);
return mDb.insert(DATABASE_NOTESTABLE, null, initialValues);
}
/**
* Create a new route using the title and body provided. If the route is
* successfully created return the new rowId for that route, otherwise return
* a -1 to indicate failure.
*
* @param start the start time of the route
* @param arrival the arrival time of the route
* @param line the line number of the route
* @param duration the routes duration
* @return rowId or -1 if failed
*/
public long createRoute(String start, String arrival, String line, String duration){
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_START, start);
initialValues.put(KEY_ARRIVAL, arrival);
initialValues.put(KEY_LINE, line);
initialValues.put(KEY_DURATION, duration);
return mDb.insert(DATABASE_ROUTESTABLE, null, initialValues);
}
/**
* Delete the note with the given rowId
*
* @param rowId id of note to delete
* @return true if deleted, false otherwise
*/
public boolean deleteNote(long rowId) {
return mDb.delete(DATABASE_NOTESTABLE, KEY_ROWID + "=" + rowId, null) > 0;
}
/**
* Return a Cursor over the list of all notes in the database
*
* @return Cursor over all notes
*/
public Cursor fetchAllNotes() {
return mDb.query(DATABASE_NOTESTABLE, new String[] {KEY_ROWID, KEY_FROM,
KEY_TO}, null, null, null, null, null);
}
/**
* Return a Cursor over the list of all routes in the database
*
* @return Cursor over all routes
*/
public Cursor fetchAllRoutes() {
return mDb.query(DATABASE_ROUTESTABLE, new String[] {KEY_ROWID, KEY_START,
KEY_ARRIVAL, KEY_LINE, KEY_DURATION}, null, null, null, null, null);
}
/**
* Return a Cursor positioned at the note that matches the given rowId
*
* @param rowId id of note to retrieve
* @return Cursor positioned to matching note, if found
* @throws SQLException if note could not be found/retrieved
*/
public Cursor fetchNote(long rowId) throws SQLException {
Cursor mCursor =
mDb.query(true, DATABASE_NOTESTABLE, new String[] {KEY_ROWID,
KEY_FROM, KEY_TO}, KEY_ROWID + "=" + rowId, null,
null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
/**
* Return a Cursor positioned at the route that matches the given rowId
*
* @param rowId id of route to retrieve
* @return Cursor positioned to matching route
* @throws SQLException if note could not be found/retrieved
*/
public Cursor fetchRoute(long rowId) throws SQLException {
Cursor mCursor =
mDb.query(true, DATABASE_ROUTESTABLE, new String[] {KEY_ROWID,
KEY_START, KEY_ARRIVAL, KEY_LINE, KEY_DURATION}, KEY_ROWID + "=" + rowId, null,
null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
/**
* Update the note using the details provided. The note to be updated is
* specified using the rowId, and it is altered to use the title and body
* values passed in
*
* @param rowId id of note to update
* @param title value to set note title to
* @param body value to set note body to
* @return true if the note was successfully updated, false otherwise
*/
public boolean updateNote(long rowId, String title, String body) {
ContentValues args = new ContentValues();
args.put(KEY_FROM, title);
args.put(KEY_TO, body);
return mDb.update(DATABASE_NOTESTABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
public void deleteRoutesTable(SQLiteDatabase db){
db.delete("routes", null, null);
}
}
我想实现像
这样的方法public void deleteTableRoutes(SQLiteDataBase db){
db.delete("routes", null, null);
}
我的问题：我想从我没有引用我的数据库（据我所知）调用此函数作为我的deleteTableRoutes（SQLiteDataBase）的参数传递...
答案 0 :(得分：1)
我认为您需要选择一个新的（更高版本）版本号，并修改您的onUpgrade方法以删除路由（如果存在）。当然，您实际上可能不需要删除现有表（例如，创建和更改可能就足够了），但这样做与您当前的实现一致。
您将使用新版本调用SQLiteOpenHelper构造函数，它将在内部调用onUpgrade，传递旧版本和新版本。
答案 1 :(得分：0)
而不是：
@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 notes");
onCreate(db);
}
我必须修改方法如下：
@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 notes");
db.execSQL("DROP TABLE IF EXISTS routes"); // line added
onCreate(db);
}
而不是：
private static final int DATABASE_VERSION = 2;
我把它改为：
private static final int DATABASE_VERSION = 3;
但是，我并不完全清楚对数据库版本的更改有真正的影响。