Develop Reference

Sync several DATA from Android SQLLite to MariaDB

i look for an easy way to sync my in SQLLite stored Data to MariaDB SQL Database.
WebService is no problem, but i have no clue to get several Data sync at once.
I had an DBAdapter with this, the id is store in sharedpreferences:
public projekt getprojekt(int id){
// 2. build projekt query
Cursor cursor =
db.query(DATABASE_TABLE_P, // a. table
TABLE_P_COLUMNS_ALL, // b. column names
" id = ?", // c. selections
new String[] { String.valueOf(id) }, // d. selections args
null, // e. group by
null, // f. having
null, // g. order by
null); // h. limit
// 3. if we got results get the first one
if (cursor != null)
cursor.moveToFirst();
// 4. build projekt object
projekt projekt = new projekt();
projekt.setId(Integer.parseInt(cursor.getString(0)));
projekt.setKostenstelle(cursor.getString(1));
projekt.setAG(cursor.getString(2));
....
// 5. return projekt
return projekt;
}
and this:
// Get Room List
public ArrayList<HashMap<String, String>> GetRaum(int pid){
ArrayList<HashMap<String, String>> raumList = new ArrayList<>();
String query = "SELECT * FROM "+ DATABASE_TABLE_R + " where pid = '"+ pid +"' order by "+KEY_R_BEZEICHNUNG+" asc";
Cursor cursor = db.rawQuery(query,null);
while (cursor.moveToNext()){
HashMap<String,String> raum = new HashMap<>();
raum.put("id",cursor.getString(cursor.getColumnIndex(KEY_M_ID)));
raum.put("bezeichnung",cursor.getString(cursor.getColumnIndex(KEY_M_BEZEICHNUNG)));
raumList.add(raum);
}
return raumList;
}
Bit how i get several "Rooms" selected to send it via POST/JSON to WebService?
My current function to send Data is not finished ... just getting the projekt_id from sharedpreferences.
public void postData() throws JSONException {
final SharedPreferences sharedPreferences = this.getSharedPreferences("de.dasal.dguvv3", Context.MODE_PRIVATE);
final Integer projektidsp = sharedPreferences.getInt("projekt_id", 0);
final projekt projekt = db.getprojekt(projektidsp);
}
If you need further Informations, please let me know.
Its my first Question on stackoverflow.

Why Sqlite return only last row not all rows data?

I don't know what's wrong with my code I follow the rule but I get wrong result. I want to search db and find all rows data but I only get last row from sqlite. my code to search database is bellow:
public ArrayList<ArrayList<ContractSaveDataFromDB>> ActiveContractData(String phone, String numberId)
{
ArrayList<ContractSaveDataFromDB> UserData = new ArrayList<ContractSaveDataFromDB>();
ArrayList<ArrayList<ContractSaveDataFromDB>> SendUserData =
new ArrayList<ArrayList<ContractSaveDataFromDB>>();
SQLiteDatabase db = this.getReadableDatabase();
String whereClause = "phone = ? AND numberId = ?";
String[] whereArgs = new String[]{
phone,
numberId
};
String orderBy = "activeContract";
Cursor res2=db.query("usersAccount",null,whereClause,whereArgs,null,null,orderBy);
res2.moveToFirst();
do{
UserData.clear();
int index;
ContractSaveDataFromDB contractSaveDataFromDB=new ContractSaveDataFromDB();
index = res2.getColumnIndex("buyAmount");
String buyAmount = res2.getString(index);
contractSaveDataFromDB.setBuyAmount(buyAmount);
UserData.add(contractSaveDataFromDB);
SendUserData.add(UserData);
} while(res2.moveToNext());
res2.close();
db.close();
return SendUserData;
I don't know what's wrong. I appreciate if you help me to solve my problem.

you already added where clause so maybe it is filtering your results try to remove it by change this
Cursor res2=db.query("usersAccount",null,whereClause,whereArgs,null,null,orderBy);
to this
Cursor res2=db.query("usersAccount",null,null,null,null,null,orderBy);

I believe that your issues is that you are trying to use an ArrayList of ArrayList of ContractSaveDataFromDB objects.
I believe that an ArrayList of ContractSaveDataFromDB objects would suffice.
It would also help you if you learnt to do a bit of basic debugging, as an issue could be that you are not extracting multiple rows.
The following is an alternative method that :-
uses the ArrayList of ContractSaveDataFromDB objects,
introduces some debugging by the way of writing some potentially useful information to the log
and is more sound, as it will not crash if no rows are extracted
i.e. if you use moveToFirst and don't check the result (false means the move could not be accomplished) then you would get an error because you are trying to read row -1 (before the first row) as no rows exists in the cursor.
:-
public ArrayList<ContractSaveDataFromDB> ActiveContractData(String phone, String numberId) {
ArrayList<ContractSaveDataFromDB> SendUserData = new ArrayList<ContractSaveDataFromDB>();
SQLiteDatabase db = this.getReadableDatabase();
String whereClause = "phone = ? AND numberId = ?";
String[] whereArgs = new String[]{
phone,
numberId
};
String orderBy = "activeContract";
Cursor res2 = db.query("usersAccount", null, whereClause, whereArgs, null, null, orderBy);
Log.d("RES2 COUNT", "Number of rows in Res2 Cursor is " + String.valueOf(res2.getCount()));
while (res2.moveToNext()) {
ContractSaveDataFromDB current_user_data = new ContractSaveDataFromDB();
current_user_data.setBuyAmount(res2.getString(res2.getColumnIndex("buyAmount")));
Log.d("NEWROW", "Adding data from row " + String.valueOf(res2.getPosition()));
SendUserData.add(current_user_data);
}
res2.close();
db.close();
Log.d("EXTRACTED", "The number of rows from which data was extracted was " + String.valueOf(SendUserData.size()));
return SendUserData;
}
If after running you check the log you should see :-
A line detailing how many rows were extracted from the table
A line for each row (if any were extracted) saying Adding data from row ? (where ? will be the row 0 being the first)
A line saying The number of rows from which data was extracted was ? (? will be the number of elements in the array to be returned)

Updating a single column is creating sqlite syntax error

I'm not sure what I'm doing wrong, but I'm trying to update a single integer value in a column of a table to 1 from 0. When creating the database, I set all values of the column to zero using:
for (int i = 0; i < setups.length; i++) {
ContentValues values = new ContentValues();
values.put(JokeDbContract.TblJoke.COLUMN_NAME_SETUP, setups[i]);
values.put(JokeDbContract.TblJoke.COLUMN_NAME_PUNCHLINE, punchlines[i]);
values.put(JokeDbContract.TblJoke.COLUMN_NAME_USED, 0);
db.insert(JokeDbContract.TblJoke.TABLE_NAME, null, values);
}
Then, in the actual activity, I'm doing:
private void findNewJoke() {
JokeDb jokeDb = JokeDb.getInstance(this);
SQLiteDatabase theDb = jokeDb.getDB();
String selection = JokeDbContract.TblJoke.COLUMN_NAME_USED + "=" + 0;
// Query database for a joke that has not been used, update the fields
// theJoke and thePunchline appropriately
String[] columns = {JokeDbContract.TblJoke._ID,
JokeDbContract.TblJoke.COLUMN_NAME_PUNCHLINE,
JokeDbContract.TblJoke.COLUMN_NAME_SETUP,
JokeDbContract.TblJoke.COLUMN_NAME_USED};
Cursor c = theDb.query(JokeDbContract.TblJoke.TABLE_NAME, columns, selection,
null, null, null, null);
if (c.moveToFirst() == false) {
Toast.makeText(this, R.string.error_retrieving_joke, Toast.LENGTH_LONG).show();
Log.e(getString(R.string.app_name),"No jokes retreived from DB in JokeActivity.findNewJoke()!");
}
else {
ContentValues values = new ContentValues();
theSetup = c.getString(c.getColumnIndexOrThrow(JokeDbContract.TblJoke.COLUMN_NAME_SETUP));
thePunchline = c.getString(c.getColumnIndexOrThrow(JokeDbContract.TblJoke.COLUMN_NAME_PUNCHLINE));
String updateSelection = JokeDbContract.TblJoke.COLUMN_NAME_SETUP + "=" + theSetup;
values.put(JokeDbContract.TblJoke.COLUMN_NAME_USED, 1);
theDb.update(JokeDbContract.TblJoke.TABLE_NAME, values, updateSelection, null);
}
}
I'm getting an error on the update:
java.lang.RuntimeException: .... while compiling: UPDATE jokes SET used=?
WHERE setup=Why do programmers always mix up Halloween and Christmas?
It seems as though I'm not getting an actual value set for the used column. What the program ultimately does is cycle through jokes where used=0, then sets used to 1 when it has been viewed. So the query only pulls those jokes that aren't used yet. I have a feeling I'm missing something simple, one can hope.

I think you are having problems with quotation marks.
Example:
String updateSelection = JokeDbContract.TblJoke.COLUMN_NAME_SETUP + "=\"" + theSetup + "\"";
However, the recommended way to do this, would be:
theDb.update(JokeDbContract.TblJoke.TABLE_NAME, values, JokeDbContract.TblJoke.COLUMN_NAME_SETUP + " = ?", new String[] { theSetup });
It is better to use field = ?, because this helps sqlite cache queries (I believe).

android sqlite query optimisation

I have an SQLite db with about 400 000 entries. To query the db I am using the following method:
public double lookUpBigramFrequency(String bigram) throws SQLException {
SQLiteDatabase db = dbh.getReadableDatabase();
double frequency = 0;
bigram = bigram.toLowerCase();
String select = "SELECT frequency FROM bigrams WHERE bigram = '"
+ bigram + "'";
Cursor mCursor = db.rawQuery(select, null);
if (mCursor != null) {
if (mCursor.moveToFirst()) {
frequency = Double.parseDouble(mCursor.getString(0));
} else {
frequency = 0;
}
}
return frequency;
}
but it takes about 0.5 sec to retrieve a single entry and having few queries, it builds up and the method is executing for 10 secs. How to speeed it up?

Firstly, use an INDEX
http://www.sqlite.org/lang_createindex.html
in your case that will be something like:
CREATE INDEX idx_bigram ON bigrams (bigram)
Secondly, use '?' instead of literal query. It helps sqlite for caching requests:
String select = "SELECT frequency FROM bigrams WHERE bigram = ?";
Cursor mCursor = db.rawQuery(select, new String[]{ bigram });
Thirdly, I trust query is more efficient than rawQuery:
mCursor = dq.query("bigrams", new String[] { "frequency" }, "bigram = ?",
new String[]{ bigram }, null, null, null, null);
Fourthly, you can query several values at once (not compatible with point 2):
SELECT frequency FROM bigrams WHERE bigrams IN ('1', '2', '3')
Fifthly, you don't need to open your database every time. You should consider leaving it open.
Edit
After seeing this question IN clause and placeholders it appears you can combine 2 and 4 after all (not sure it is useful, though)

Always use transaction mechanism when you want to do lots of database operations
public static void doLotDBOperations() {
try {
// Code to Open Database
// Start transaction
sqlDb.beginTransaction();
// Code to Execute all queries
sqlDb.setTransactionSuccessful();
} catch (Exception e) {
e.printStackTrace();
} finally {
// End all transaction
sqlDb.endTransaction();
// Code to Close Database
}
}

Android SQLite rawquery returns only first record

My SQLite query returning only one record, However, the table has multiple rows
cursor=mydb.rawQuery("Select category from items;", null);
I have even tried GROUP BY but still wont work.
I am new to SQLite, would appreciate any help. Thanks.

First of all your string query must not be terminated so instead of passing it as:
"Select category from items;"
you should try passing it as:
"Select category from items"
as mentioned on this page.
Also, are you looping over the cursor? Here is an example of how to get data out of a cursor with a while loop:
ArrayList<String> results = new ArrayList<String>()
while (cursor.moveNext()) {
results.add(cursor.getString(0)); // 0 is the first column
}

First, search:
Cursor cs = myDataBase.rawQuery("Your query", null);
if (cs.moveToFirst()) {
String a = cs.getString(cs.getColumnIndex("your_column_name"));
cs.close();
return a;
}
cs.close();
return "";
Get the information from cursor:
if (cs.moveToFirst()) {
ArrayList<String> results = new ArrayList<String>()
do {
results.add(cs.getString(cs.getColumnIndex("your_column_name")));
} while (cs.moveNext());
}
Without if, I took error in my project. But this worked for me. By the way, your query doesn't look good. If you give some information about your database, we can help much more.

Use this to select all items from the table:
Cursor cursor = db.rawQuery("SELECT * FROM Tablename ,
null);

this can help you
public ArrayList<mydata> getallContents() {
ArrayList<mydata> lst = new ArrayList<mydata>();
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery("select * from " + GAMETABLE, null);
if (c.moveToFirst()) {
do {
lst.add(new mydata(c.getString(1),
c.getString(3),c.getString(4),c.getString(5),c.getString(6)));
} while (c.moveToNext());
}
db.close();
return lst;
}

you don't need raw query method. i think that the android way is better in this case:
db.query(items, category, null, null, null, null, null);
than use the cursor how already is written in the other comment.