Develop Reference

how to check if sqlite database is empty (android)?

I am making a media player which loads metadata of songs into a database.
Below is my function for checking whether the db is empty or not but it isn't working. Please tell me what's wrong with my code and suggest a correction or a better alternative.
private static boolean isDbEmpty(SQLiteDatabase songsDb) {
try {
Cursor c = songsDb.rawQuery("SELECT * FROM " + SongsTable.TABLE_NAME, null);
if (c.moveToFirst()) { // c.getCount() == 0 is also not working
Log.d(TAG, "isDbEmpty: not empty");
return false;
}
c.close();
} catch (SQLiteException e) {
Log.d(TAG, "isDbEmpty: doesn't exist");
return true;
}
return true;
}

Use the following query to achieve your goal. There are two tables created automatically - android_metadata and sqlite_sequence, so we apply a NOT condition in the query.
SELECT count(*) FROM sqlite_master WHERE type = 'table' AND name != 'android_metadata' AND name != 'sqlite_sequence';

Try this.
private static boolean isDbEmpty(SQLiteDatabase songsDb) {
Cursor c = null;
try {
c = songsDb.rawQuery("SELECT * FROM " + SongsTable.TABLE_NAME, null);
if (c == null || c.getCount() == 0) {
return true;
} else if (c.moveToFirst()) {
Log.d(TAG, "isDbEmpty: not empty");
return false;
}
} catch (SQLiteException e) {
Log.d(TAG, "isDbEmpty: doesn't exist");
return true;
}finally {
if(c != null){
c.close();
}
}
return true;
}

This will only tell you if the TABLE is empty, not the DATABASE.
Regardless, you could use code like:
Cursor countCursor = songsDb.rawQuery("select count(*) from " + SongsTable.TABLE_NAME, null);
countCursor.moveToFirst();
int count = countCursor.getInt(0);
countCursor.close();
And then test count.

You can check like this :
Cursor c = songsDb.rawQuery("SELECT * FROM " + SongsTable.TABLE_NAME, null);
cursor.moveToFirst();
if (cursor != null && cursor.getCount() == 0) {
//for empty
return true;
}else{
// not empty
return false;
}

Can't set a paging contact list in android

My app is taking forever to load,how can I use paging that's it would load me like 10-15 people in a page and not to take 2 minute to my app for loading??
this is my code:
thank's for the help
public class Contacts extends Util<Contact> {
public Contacts(Activity activity) {
super(activity);
}
#Override
public void init() {
list = getContactsBasic();
for (int i = 0; i < list.size(); i++) {
Contact current = list.get(i);
current.image = getContactImage(current.id);
if (current.hasPhone) {
current.phones = getContactPhones(current.id);
}
}
}
LinkedList<Contact> getContactsBasic() {
Uri contactsUri = android.provider.ContactsContract.Contacts.CONTENT_URI;
Cursor cursor = activity.getContentResolver().query(contactsUri, null, null, null, null);
LinkedList<Contact> list = new LinkedList<Contact>();
if (cursor != null) {
if (cursor.moveToFirst()) {
do {
int id = cursor.getInt(cursor.getColumnIndex(android.provider.ContactsContract.Contacts._ID));
String name = cursor.getString(cursor.getColumnIndex(android.provider.ContactsContract.Contacts.DISPLAY_NAME));
int hasPhone = cursor.getInt(cursor.getColumnIndex(android.provider.ContactsContract.Contacts.HAS_PHONE_NUMBER));
// add more columns here
boolean hasPhoneBoolean; //editor: or simply: boolean hasPhoneBoolean = (hasPhone == 1)
if (hasPhone == 1){
hasPhoneBoolean = true;
}
else {
hasPhoneBoolean = false;
}
Contact contact = new Contact(id, name, hasPhoneBoolean);
//Contact contact = new Contact(id, name, (hasPhone == 1) ? true : false);
list.add(contact);
}
while (cursor.moveToNext());
}
cursor.close();
}
return list;
}
LinkedList<Phone> getContactPhones(int id) {
Uri phonesUri = android.provider.ContactsContract.CommonDataKinds.Phone.CONTENT_URI;
String filter = android.provider.ContactsContract.CommonDataKinds.Phone.CONTACT_ID + " = " + String.valueOf(id);
Cursor cursor = activity.getContentResolver().query(phonesUri, null, filter, null, null);
LinkedList<Phone> list = new LinkedList<Phone>();
if (cursor != null) {
if (cursor.moveToFirst()) {
do {
String number = cursor.getString(cursor.getColumnIndex(android.provider.ContactsContract.CommonDataKinds.Phone.NUMBER));
int type = cursor.getInt(cursor.getColumnIndex(android.provider.ContactsContract.CommonDataKinds.Phone.TYPE));
Phone phone = new Phone(number, type);
list.add(phone);
}
while (cursor.moveToNext());
}

Change
Cursor cursor = activity.getContentResolver().query(contactsUri, null, null, null, null);
to
Cursor cursor = activity.getContentResolver().query(contactsUri, null, null, null, "ASC LIMIT " + HOW_MANY_ROWS_YOU_NEED);

Sqlite Check if Table is Empty [duplicate]

This question already has answers here:
How can i check to see if my sqlite table has data in it?
(13 answers)
Closed 4 years ago.
Well, I have a databse and it has lots of table. but generally tables are empty.
I want check if a database table is empty.
IF table is empty, program will fill it.
public static long queryNumEntries (SQLiteDatabase db, String table)
I will use it but it requre API 11.

you can execute select count(*) from table and check if count> 0 then leave else populate it.
like
SQLiteDatabase db = table.getWritableDatabase();
String count = "SELECT count(*) FROM table";
Cursor mcursor = db.rawQuery(count, null);
mcursor.moveToFirst();
int icount = mcursor.getInt(0);
if(icount>0)
//leave
else
//populate table

Do a SELECT COUNT:
boolean empty = true
Cursor cur = db.rawQuery("SELECT COUNT(*) FROM YOURTABLE", null);
if (cur != null && cur.moveToFirst()) {
empty = (cur.getInt (0) == 0);
}
cur.close();
return empty;

public boolean isEmpty(String TableName){
SQLiteDatabase database = this.getReadableDatabase();
long NoOfRows = DatabaseUtils.queryNumEntries(database,TableName);
if (NoOfRows == 0){
return true;
} else {
return false;
}
}

Optimal Solutions
public boolean isMasterEmpty() {
boolean flag;
String quString = "select exists(select 1 from " + TABLE_MASTERS + ");";
SQLiteDatabase db = getReadableDatabase();
Cursor cursor = db.rawQuery(quString, null);
cursor.moveToFirst();
int count= cursor.getInt(0);
if (count ==1) {
flag = false;
} else {
flag = true;
}
cursor.close();
db.close();
return flag;
}

Here is a better option:
public boolean validateIfTableHasData(SQLiteDatabase myDatabase,String tableName){
Cursor c = myDatabase.rawQuery("SELECT * FROM " + tableName,null);
return c.moveToFirst();
}

This is how you can do it -
if(checkTable("TABLE"))
{
//table exists fill data.
}
Method to check table -
public static boolean checkTable(String table) {
Cursor cur2 = dbAdapter.rawQuery("select name from sqlite_master where name='"
+ table + "'", null);
if (cur2.getCount() != 0) {
if (!cur2.isClosed())
cur2.close();
return true;
} else {
if (!cur2.isClosed())
cur2.close();
return false;
}
}

I think, this solution is better:
boolean flag;
DatabaseHelper databaseHelper = new DatabaseHelper(getApplicationContext(), DatabaseHelper.DATABASE_NAME, null, DatabaseHelper.DATABASE_VERSION);
try {
sqLiteDatabase = databaseHelper.getWritableDatabase();
} catch (SQLException ex) {
sqLiteDatabase = databaseHelper.getReadableDatabase();
}
String count = "SELECT * FROM table";
Cursor cursor = sqLiteDatabase.rawQuery(count, null);
if (cursor.moveToFirst()){
flag = false;
} else {
flag = true;
}
cursor.close();
sqLiteDatabase.close();
return flag;
moveToFirst() check table and return true, if table is empty. Answer that is marked correct - uses extra check.

retrieving record from database using cursor in android

I have used following codes to retrieve record:
String getCredentialsFromAdmint(String name ,String pwd) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_ADMIN, new String[] { KEY_ID,
KEY_A_USER_NAME, KEY_A_PWD }, KEY_A_USER_NAME + "=?" + " AND " + KEY_A_PWD + "=?",
new String[] { name , pwd }, null, null, null, null);
if (cursor != null){
cursor.moveToFirst();
return cursor.getString(1);
}
else{
return "norecord";
}
This code works if there is a record but if no record is found then application gets an error.
Is there any other ways to retrieve data from database?

Change your code to following
if ( cursor.moveToFirst()){
return cursor.getString(1);
} else{
return "norecord";
}

You don't check if cursor.moveToFirst() returns true;
It should looks like this:
if (cursor != null) {
if(cursor.moveToFirst()){
return cursor.getString(cursor.getColumnIndexOrThrow(KEY_A_USER_NAME));
} else{
//no record
}
} else {
//invalid uri
}

Try to use the following code instead
if (cursor != null){
cursor.moveToFirst();
if(cursor.isAfterLast() == false) {
return cursor.getString(1);
}
else
{
return "norecord";
}
}
else{
return "norecord";
}

getting data from database table using cursor in android

I have one employee table which has column values
("store_loc_id","name","password","address_id","role_id",
"retailer_id").
I want to get the name and password from this table using cursor. how can i do??

Haven't check this code, but the idiom should be understandable.
Cursor cursor = db.query(...);
if(cursor !=null && cursor.moveToFirst()) {
do {
String name = cursor.getString(cursor.getColumnIndex("name"));
} while (cursor.moveToNext());
}

public Cursor getEmployee() {
try {
return db.query(employee, new String[] { "name", "password" },
null, null, null, null, null);
} catch (SQLException e) {
Log.e("Exception on query", e.toString());
return null;
}
}
Cursor c = db.getEmployee();
if (c == null) {
// do nothing
} else {
if (c.getCount() > 0) {
if (c.moveToFirst()) {
do {
String Name = c.getString(0);
String Password = c.getString(1);
} while (c.moveToNext());
}
}
}