I had a problem which I already solved but I still wants to know WHY
the solution solved it.
I wrote an android app that had a sqlite db after a couple of times I debugged it
The oncreate method in the db didnt got called (even though everything worked fine before)
After I changed the db version number from 1 to 2 everything worked fine again
Even though I uninstalled the app through the app manager and also removed the cache and
The local database information.
My question is as follows - does the local database data is saved somewhere else?
In case it doesn't - Why did it worked only after I upgraded the version number
not even when I erased all the app related data?
/**
* A class to handle sqlite reads/writes of user related data to be collected
*/
public class UserDataManager extends SQLiteOpenHelper {
// Class Variables
private final String TAG = UserDataManager.class.getSimpleName();
// Database Version
private static final int DATABASE_VERSION = 1;
// Database Name
public static final String DATABASE_NAME = "tmc";
// Tables
private static final String TABLE_USER = "user";
// Tables and table columns names
private String CREATE_USER_TABLE;
private static final String COLUMN_USER_ID = "user_id";
private static final String COLUMN_USER_MAIL = "email";
private static final String COLUMN_USER_ACTIVE = "user_active";
private static final String COLUMN_USER_NAME = "name";
private static final String COLUMN_USER_PASSWORD = "password";
private static final String COLUMN_USER_PHONE_NUMBER = "phone_number";
/**
* Class constructor
*
* @param context
* The context to run in
*/
public UserDataManager(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
CREATE_USER_TABLE = "CREATE TABLE IF NOT EXISTS " + TABLE_USER + " ("
+ COLUMN_USER_ID + " INTEGER PRIMARY KEY NOT NULL, "
+ COLUMN_USER_MAIL + " VARCHAR(64) NOT NULL, "
+ COLUMN_USER_NAME + " VARCHAR(64) NOT NULL, "
+ COLUMN_USER_PASSWORD + " VARCHAR(64) NOT NULL, "
+ COLUMN_USER_PHONE_NUMBER + " VARCHAR(64) NOT NULL, "
+ COLUMN_USER_ACTIVE + " INT NOT NULL);";
// create the tables
db.execSQL(CREATE_USER_TABLE);
}
// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// Drop older table if existed
db.execSQL("DROP TABLE IF EXISTS " + TABLE_USER);
// Create tables again
onCreate(db);
}
/**
* Adding a user to the database
*
* @param userId
* The created user id
* @param userName
* The user name
* @param userEmail
* The user email
* @param userPassword
* The user password
* @param userPhoneNumber
* The user phone number
* @param isActive
* Set to 1 if the user is active 0 otherwise
* @return True if the user added successfully false otherwise
*/
public boolean AddUser(int userId, String userName, String userEmail,
String userPassword, String userPhoneNumber, boolean isActive) {
// method variables
long rowId;
boolean pass = false;
int active = isActive ? 1 : 0;
SQLiteDatabase db = null;
ContentValues row = null;
// try to add the user to the db
try {
row = new ContentValues();
db = this.getWritableDatabase();
db.delete(TABLE_USER, null, null);
row.put(COLUMN_USER_ID, userId);
row.put(COLUMN_USER_NAME, userName);
row.put(COLUMN_USER_MAIL, userEmail);
row.put(COLUMN_USER_PASSWORD, userPassword);
row.put(COLUMN_USER_CAR_NUMBER, userPhoneNumber);
row.put(COLUMN_USER_ACTIVE, active);
rowId = db.insert(TABLE_USER, null, row);
if (rowId > -1) {
pass = true;
}
} catch (SQLException exception) {
Log.e(TAG, exception.getMessage());
} finally {
if (db != null) {
// close database connection
db.close();
}
}
return pass;
}
/**
* Get the current registered user
*
* @return The id of the column of the registered user
*/
public int GetRegisteredUserId() {
// method variables
int columnIndex = -1;
int userId = -1;
SQLiteDatabase db = null;
Cursor cursor = null;
// try to get the user from the database
try {
db = this.getReadableDatabase();
cursor = db.query(TABLE_USER, new String[] { COLUMN_USER_ID },
null, null, null, null, null);
if (cursor != null) {
boolean moved = cursor.moveToFirst();
if (moved) {
columnIndex = cursor.getColumnIndex(COLUMN_USER_ID);
if (columnIndex > -1) {
userId = cursor.getInt(columnIndex);
}
}
}
} catch (SQLException exception) {
Log.e(TAG, exception.getMessage());
} finally {
if (cursor != null)
// release cursor
cursor.close();
if (db != null)
// close database connection
db.close();
}
return userId;
}
/**
* Get the current user email
*
* @return The id of the column of the registered user
*/
public String GetRegisteredUserEmail() {
// method variables
int columnIndex = -1;
String userEmail = null;
SQLiteDatabase db = null;
Cursor cursor = null;
// try to get the user from the database
try {
db = this.getReadableDatabase();
cursor = db.query(TABLE_USER, new String[] { COLUMN_USER_MAIL },
null, null, null, null, null);
if (cursor != null) {
boolean moved = cursor.moveToFirst();
if (moved) {
columnIndex = cursor.getColumnIndex(COLUMN_USER_MAIL);
if (columnIndex > -1) {
userEmail = cursor.getString(columnIndex);
}
}
}
} catch (SQLException exception) {
Log.e(TAG, exception.getMessage());
} finally {
if (cursor != null)
// release cursor
cursor.close();
if (db != null)
// close database connection
db.close();
}
return userEmail;
}
/**
* Get the current user password
*
* @return The password of the current logged user
*/
public String GetRegisteredUserPassword() {
// method variables
int columnIndex = -1;
String userPassword = null;
SQLiteDatabase db = null;
Cursor cursor = null;
// try to get the user from the database
try {
db = this.getReadableDatabase();
cursor = db.query(TABLE_USER,
new String[] { COLUMN_USER_PASSWORD }, null, null, null,
null, null);
if (cursor != null) {
boolean moved = cursor.moveToFirst();
if (moved) {
columnIndex = cursor.getColumnIndex(COLUMN_USER_PASSWORD);
if (columnIndex > -1) {
userPassword = cursor.getString(columnIndex);
}
}
}
} catch (SQLException exception) {
Log.e(TAG, exception.getMessage());
} finally {
if (cursor != null)
// release cursor
cursor.close();
if (db != null)
// close database connection
db.close();
}
return userPassword;
}
/**
* Get number of rows in the user table
*
* @return the number of the rows in the user table (How many users are
* saved in the DB)
*/
public int GetRowCount() {
// method variables
int rowsCount = 0;
SQLiteDatabase db = null;
Cursor cursor = null;
// try to get the user from the database
try {
db = this.getReadableDatabase();
cursor = db.query(TABLE_USER, null, null, null, null, null, null);
if (cursor != null) {
boolean moved = cursor.moveToFirst();
if (moved) {
do {
rowsCount++;
} while (cursor.moveToNext());
}
}
} catch (SQLException exception) {
Log.e(TAG, exception.getMessage());
} finally {
if (cursor != null)
// release cursor
cursor.close();
if (db != null)
// close database connection
db.close();
}
return rowsCount;
}
/**
* Remove a user from the database
*
* @param userId
* The user id
*/
public void LogoutUser() {
// method variables
SQLiteDatabase db = null;
// try to remove a user from the database
try {
db = this.getWritableDatabase();
onUpgrade(db, DATABASE_VERSION, DATABASE_VERSION);
} catch (SQLException exception) {
Log.e(TAG, exception.getMessage());
} finally {
if (db != null) {
// close database connection
db.close();
}
}
}
/**
* Set a user to be active or not
*
* @param isActive
* 1 if the cigarette is active 0 otherwise
* @return True if the cigarette active field has changed false otherwise
*/
public boolean SetUserActive(boolean isActive) {
// method variables
int rowsAffected;
int active = isActive ? 1 : 0;
long userId;
String userIdString;
boolean pass = true;
SQLiteDatabase db = null;
ContentValues values = null;
// try to remove a device from the database
try {
userId = GetRegisteredUserId();
if (userId > -1) {
userIdString = String.valueOf(userId);
db = this.getWritableDatabase();
values = new ContentValues();
values.put(COLUMN_USER_ACTIVE, active);
rowsAffected = db.update(TABLE_USER, values, COLUMN_USER_ID
+ " = ?", new String[] { userIdString });
if (rowsAffected != 1) {
pass = false;
}
}
} catch (SQLException exception) {
Log.e(TAG, exception.getMessage());
} finally {
if (db != null) {
// close database connection
db.close();
}
}
return pass;
}
}
Notes -
1. Please note that my device is rooted and so after inserting the data to the db im
changing the permissions on the db file for 777 so I can pull it from the phone to see
whats in it (i.e. did the query pass or not)
2. The error that is being thrown is "android.database.sqlite.SQLiteException: no such
table: user "
Chocolate chips cookies will be granted for any answer... =)