我已经使用一些教程编写了登录功能来存储用户名和密码。它工作得很好。一段时间后，我需要在单个数据库中管理两个表。我是通过关注这个网站实现的。
但我没有这样的表错误。任何帮助，将不胜感激。这是我的代码：
public class LoginDataBaseAdapter{
public static final String ROW_ID = "_id";
public static final String USERNAME = "name";
public static final String PASSWORD = "password";
private static final String DATABASE_TABLE = "users";
public SQLiteDatabase db;
// Context of the application using the database.
private final Context context;
private DatabaseHelper dbHelper;
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DatabaseAdapter.DATABASE_NAME,null, DatabaseAdapter.DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase arg0) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
// TODO Auto-generated method stub
}
}
public LoginDataBaseAdapter(Context _context)
{
this.context = _context;
}
public LoginDataBaseAdapter open() throws SQLException
{
this.dbHelper = new DatabaseHelper(this.context);
this.db = this.dbHelper.getWritableDatabase();
return this;
}
public void close()
{
dbHelper.close();
}
public void createUsers(String name, String pass){
ContentValues initialValues = new ContentValues();
initialValues.put(USERNAME, name);
initialValues.put(PASSWORD, pass);
db.insert(DATABASE_TABLE, null, initialValues);
}
public boolean deleteUser(long rowId) {
return this.db.delete(DATABASE_TABLE, ROW_ID + "=" + rowId, null) > 0;
}
public Cursor getAllUsers() {
return this.db.query(DATABASE_TABLE, new String[] { ROW_ID,
USERNAME, PASSWORD }, null, null, null, null, null);
}
public String getUser(String username) throws SQLException {
Cursor cursor=db.query(DATABASE_TABLE, null, " USERNAME=?", new String[]{username}, null, null, null);
if(cursor.getCount()<1) // UserName Not Exist
{
cursor.close();
return "NOT EXIST";
}
cursor.moveToFirst();
String password= cursor.getString(cursor.getColumnIndex("PASSWORD"));
cursor.close();
return password;
}
public boolean updateUser(long rowId, String name, String pass,
String year){
ContentValues args = new ContentValues();
args.put(USERNAME, name);
args.put(PASSWORD, pass);
return this.db.update(DATABASE_TABLE, args, ROW_ID + "=" + rowId, null) >0;
}
public SQLiteDatabase getDatabaseInstance()
{
return db;
}
/*public void insertEntry(String userName,String password)
{
ContentValues newValues = new ContentValues();
// Assign values for each row.
newValues.put("USERNAME", userName);
newValues.put("PASSWORD",password);
// Insert the row into your table
db.insert("LOGIN", null, newValues);
///Toast.makeText(context, "Reminder Is Successfully Saved", Toast.LENGTH_LONG).show();
}
public int deleteEntry(String UserName)
{
//String id=String.valueOf(ID);
String where="USERNAME=?";
int numberOFEntriesDeleted= db.delete("LOGIN", where, new String[]{UserName}) ;
// Toast.makeText(context, "Number fo Entry Deleted Successfully : "+numberOFEntriesDeleted, Toast.LENGTH_LONG).show();
return numberOFEntriesDeleted;
} */
/* public String getSinlgeEntry(String userName)
{
Cursor cursor=db.query("LOGIN", null, " USERNAME=?", new String[]{userName}, null, null, null);
if(cursor.getCount()<1) // UserName Not Exist
{
cursor.close();
return "NOT EXIST";
}
cursor.moveToFirst();
String password= cursor.getString(cursor.getColumnIndex("PASSWORD"));
cursor.close();
return password;
}*/
/*public void updateEntry(String userName,String password)
{
// Define the updated row content.
ContentValues updatedValues = new ContentValues();
// Assign values for each row.
updatedValues.put("USERNAME", userName);
updatedValues.put("PASSWORD",password);
String where="USERNAME = ?";
db.update("LOGIN",updatedValues, where, new String[]{userName});
}
*/
}
这是我的Adapter类：
public class DatabaseAdapter {
// public static final String DATABASE_NAME = "example";
public static final int DATABASE_VERSION = 1;
private static final String CREATE_TABLE_USERS =
"create table users (_id integer primary key autoincrement, "
+ LoginDataBaseAdapter.USERNAME+ " TEXT,"
+ LoginDataBaseAdapter.PASSWORD+ " TEXT,"
+ ");";
private static final String CREATE_TABLE_REMIND = "create table remind (_id integer primary key autoincrement, " //$NON-NLS-1$
+MedicationDBAdapter.MEDICINAME+" TEXT,"
+MedicationDBAdapter.MEDICINEDIR+" TEXT,"
+ ");";
public static final String DATABASE_NAME="example.db";
private final Context context;
private DatabaseHelper DBHelper;
private SQLiteDatabase db;
public DatabaseAdapter(Context ctx)
{
this.context = ctx;
this.DBHelper = new DatabaseHelper(this.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(CREATE_TABLE_USERS);
db.execSQL(CREATE_TABLE_REMIN);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
// Adding any table mods to this guy here
}
}
/**
* open the db
* @return this
* @throws SQLException
* return type: DBAdapter
*/
public DatabaseAdapter open() throws SQLException
{
this.db = this.DBHelper.getWritableDatabase();
return this;
}
/**
* close the db
* return type: void
*/
public void close()
{
this.DBHelper.close();
}
}
答案 0 :(得分：0)
尝试这样的东西，看起来更整洁（我有4张桌子）：
public class DatabaseHelper extends SQLiteOpenHelper
{
private static final String TAG = "DatabaseHelper";
private static DatabaseHelper sInstance = null;
private static final String DATABASE_NAME = "dbname";
private static final int DATABASE_VERSION = 1;
@Override
public void onCreate(SQLiteDatabase db)
{
// create books table
String sql = "CREATE TABLE [Book] ([_id] INTEGER NOT NULL PRIMARY KEY, [Arabic] TEXT, [English] TEXT)";
db.execSQL(sql);
// create hadiths table
sql = "CREATE TABLE [Hadith] ([_id] INTEGER NOT NULL PRIMARY KEY, [Arabic] TEXT, [English] TEXT, [Urdu] TEXT, [Indonesian] TEXT, [Book] INTEGER NOT NULL, FOREIGN KEY(Book) REFERENCES Book(_id))";
db.execSQL(sql);
// add index on hadiths table
sql = "CREATE INDEX [FK_Book] ON [Hadith]([Book] ASC)";
db.execSQL(sql);
// create bookmarks table
sql = "CREATE TABLE [Bookmark] ([_id] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, [Hadith] INTEGER NOT NULL, [Summary] TEXT)";
db.execSQL(sql);
// create settings table
sql = "CREATE TABLE [Setting] ([_id] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT, [Name] TEXT, [Value] TEXT)";
db.execSQL(sql);
// add a sample book
sql = "INSERT INTO Book (_id,Arabic,English) VALUES(1,'كتاب بدء الوحى','Revelation')";
db.execSQL(sql);
// insert sample hadith
sql = "INSERT INTO Hadith (_id,Arabic,English,Urdu,Indonesian,Book) VALUES(1,'English...','Arabic...','Urdu...','Indonesian...',1)";
db.execSQL(sql);
// insert sample bookmark
sql = "INSERT INTO Bookmark (Hadith,Summary) VALUES(1,'Summary...')";
db.execSQL(sql);
// insert default settings
sql = "INSERT INTO Setting (Name,Value) VALUES('FontSize','17')";
db.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
Log.w(DatabaseHelper.class.getName(), "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS Setting");
db.execSQL("DROP TABLE IF EXISTS Bookmark");
db.execSQL("DROP TABLE IF EXISTS Hadith");
db.execSQL("DROP TABLE IF EXISTS Book");
onCreate(db);
}
public static DatabaseHelper getInstance(Context context)
{
// Use the application context, which will ensure that you
// don't accidentally leak an Activity's context.
// See this article for more information: http://bit.ly/6LRzfx
if (sInstance == null)
{
sInstance = new DatabaseHelper(context.getApplicationContext());
}
return sInstance;
}
/**
* Constructor should be private to prevent direct instantiation.
* make call to static factory method "getInstance()" instead.
*/
private DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
}
然后使用以下代码从代码的任何部分调用它：
// get list of books from db
DatabaseHelper dbHelper = DatabaseHelper.getInstance(this);
SQLiteDatabase db = dbHelper.getReadableDatabase();
final Cursor cursor = db.rawQuery("SELECT * FROM Book", null);
while(cursor.moveToNext())
{
bookNames.add(cursor.getString(2));
}