Develop Reference

How to return a string value from sqlite query?

Here is my query. I want to get the string value and return the single value to the activity class from where I have called the getSelectedMerchantCode function. My code is not working. Its returning "error"
public String getSelectedMerchantCode(String merchantname){
String selection = "Error";
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery("SELECT merchantCode FROM " + "merchantList"+ " WHERE " + "merchantName" + "='" + merchantname + "'", null);
if(c.getCount() == 1){
c.moveToFirst();
selection = c.getString(c.getColumnIndex("merchantCode"));
return selection;
}
c.close();
db.close();
return null;
}

Try this way..
public List<String> getMyItems(String name) {
List<String> stringList = new ArrayList<>();
SQLiteDatabase db = this.getReadableDatabase();
String selectQuery = "SELECT Item_Name FROM " + USER_TABLE_NAME + " WHERE Item_Name= " + name;
Cursor c = db.rawQuery(selectQuery, null);
if (c != null) {
c.moveToFirst();
while (c.isAfterLast() == false) {
String name = (c.getString(c.getColumnIndex("Item_Name")));
stringList.add(name);
c.moveToNext();
}
}
return stringList;
}

rawQuery() exact match

I am using the following method to query my SQLite database with LIKE statement.
public List<Bean> getWords(String englishWord) {
if(englishWord.equals(""))
return new ArrayList<Bean>();
String sql = "SELECT * FROM " + TABLE_NAME +
" WHERE " + ENGLISH + " LIKE ? ORDER BY LENGTH(" + ENGLISH + ") LIMIT 100";
SQLiteDatabase db = initializer.getReadableDatabase();
Cursor cursor = null;
try {
cursor = db.rawQuery(sql, new String[]{"%" + englishWord.trim() + "%"});
List<Bean> wordList = new ArrayList<Bean>();
while(cursor.moveToNext()) {
String english = cursor.getString(1);
String mal = cursor.getString(2);
wordList.add(new Bean(english, bangla));
}
return wordList;
} catch (SQLiteException exception) {
exception.printStackTrace();
return null;
} finally {
if (cursor != null)
cursor.close();
}
}
I would like to change the above code for that it will query for exact match. I tried to modify the code as below but I do not how to get the mal string.
public void getoneWords(String englishWord) {
String sql = "SELECT * FROM " + TABLE_NAME +
" WHERE " + ENGLISH + " =?";
SQLiteDatabase db = initializer.getReadableDatabase();
Cursor cursor = null;
try {
cursor = db.rawQuery(sql, new String[]{englishWord});
while(cursor.moveToNext()) {
String english = cursor.getString(1);
String mal = cursor.getString(2);
}
} finally {
if (cursor != null)
cursor.close();
}
}

Method getoneWords for what. You should return mal and english in this function.
return new Bean(english, mal);
If you need first word, just cursor.moveToFirst and delete while loop:
String english = cursor.getString(1);
String mal = cursor.getString(2);
return new Bean(english, mal);

I finally solved this problem myself.
public String getoneWords(String englishWord) {
String sql = "SELECT * FROM " + TABLE_NAME +
" WHERE " + ENGLISH + " =?";
SQLiteDatabase db = initializer.getReadableDatabase();
Cursor cursor = null;
String meaning = "";
try {
cursor = db.rawQuery(sql, new String[] {englishWord});
if(cursor.getCount() > 0) {
cursor.moveToFirst();
meaning = cursor.getString(2);
}
return meaning;
}finally {
cursor.close();
}
}

In your getoneWords() you are not returning the queried values.
As you have two return values you would either need to wrap them in a Pair or create a "holder" Object (e.g. class Words(String english, String mal)) for the return values.
If your Query returns multiple matches you would need to return a list of those Objects. Otherwise, your above Code would just return the last match.
So you need to alter your function to return the queried
public Pair<String,String> getoneWords(String englishWord) {
Pair<String,String> result = null;
...
if(cursor.moveToNext()) {
String english = cursor.getString(1);
String mal = cursor.getString(2);
result = new Pair<String,String>(english, mal);
}
...
return result;
}

Database is not retrieving all rows instead getting only unique rows

I am working on a code snippet where i am storing my json encoded data into a txt file,and using following method to separate all parts and adding them into database.
public boolean addAnswersFromJSONArray() {
boolean flag = false;
Answer answer = new Answer();
File sdcard = Environment.getExternalStorageDirectory();
File file = new File(sdcard, "user_live.txt");
FileReader fr;
JsonReader reader;
try {
fr = new FileReader(file);
reader = new JsonReader(fr);
reader.beginArray();
reader.setLenient(true);
while (reader.hasNext()) {
reader.beginObject();
while (reader.hasNext()) {
String name = reader.nextName();
if (name.equals("product_name")) {
answer.setProductName(reader.nextString());
} else if (name.equals("subject")) {
answer.setSubject(reader.nextString());
} else if (name.equals("month")) {
answer.setMonth(reader.nextString());
} else if (name.equals("year")) {
answer.setYear(reader.nextString());
} else if (name.equals("question")) {
answer.setQuestion(reader.nextString());
} else if (name.equals("answer")) {
answer.setAnswer(reader.nextString());
} else if (name.equals("question_no")) {
answer.setQuestion_no(reader.nextString());
} else if (name.equals("marks")) {
answer.setMarks(reader.nextString());
} else {
reader.skipValue();
}
}
answer.save(db);
reader.endObject();
flag = true;
}
reader.endArray();
reader.close();
} catch (Exception e) {
e.printStackTrace();
} finally {
file.delete();
db.close();
}
return flag;
}
and then i am retrieving each fields departments,subjects,month and year,questions,answers,question_no, but while retrieving marks i am getting only unique entries that is 10 and 5....Ideally the size of one set is 18 so i m getting ArrayIndexoutOfBounds Exception.
//database calling part
marks = db.getMarksList(department, subject, month_year);
database method is,
public String[] getMarksList(String department, String subject,
String month_year) {
String month = month_year.split("-")[0];
String year = month_year.split("-")[1];
String whereClause = DEPARTMENT + " = '" + department + "'" + " AND "
+ SUBJECT + " = '" + subject + "' AND " + MONTH + " = '"
+ month + "' AND " + YEAR + " = '" + year + "'";
System.out.println("questions: " + whereClause);
Cursor cursor = db.query(true, "ANSWERS", new String[] { "MARKS" },
whereClause, null, null, null, "DEPARTMENT", null);
String list[] = new String[cursor.getCount()];
int i = 0;
if (cursor != null && cursor.getCount() > 0) {
for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor
.moveToNext()) {
list[i] = new String(cursor.getString(0));
i++;
}
}
return list;
}
Can anyone help me to resolve this issue?? Why getting only unique value,I have checked my json result also each row contains marks.

i got the solution for this,
Changed database query and method as following,
public List<Answer> getMarksList(String department, String subject,
String month_year) {
List<Answer> list = new ArrayList<Answer>();
String month = month_year.split("-")[0];
String year = month_year.split("-")[1];
try {
String sql1 = "select all marks from " + TABLE_NAME
+ " where department = '" + department
+ "' AND subject = '" + subject + "' AND month = '" + month
+ "' AND year = '" + year + "';";
SQLiteDatabase db1 = this.getWritableDatabase();
Cursor cursor = db1.rawQuery(sql1, null);
if (cursor.moveToFirst()) {
do {
Answer a = new Answer();
a.setMarks(cursor.getString(0));
list.add(a);
} while (cursor.moveToNext());
}
} catch (Exception e) {
}
return list;
}
using "all" in query is retrieving all records.

Android SQLite rawQuery() method

I created a table with three columns id, name and discipline.
I want to find the student name given the discipline.
Following is my method:
String findstudent(String disc){
SQLiteDatabase sqLiteDatabase = this.getReadableDatabase();
String find = "SELECT * FROM "+ TABLE_STUDENTS + " WHERE "+KEY_DISCIPLINE +" = " +disc ;
Cursor cursor = sqLiteDatabase.rawQuery(find,null);
cursor.moveToFirst();
String found =cursor.getString(1);
return found;
}
When I use it, the application stops working.

I am not sure. But, you can try this way
Cursor.moveToFirst();
do{
//get the data
String found =cursor.getString(cursor.getColumnIndexOrThrow("COLUMN NAME"));
}while(Cursor.moveNext);

Try the following code:
String find = "SELECT *<enter code here>
FROM "+ TABLE_STUDENTS + "
WHERE "+KEY_DISCIPLINE +" = '" + disc + "'" ;

Try this:
String findstudent(String disc){
Cursor cursor;
cursor = this.db.query(TABLE_STUDENTS,null, KEY_DISCIPLINE +" = "+ disc, null, null, null, null,null );
cursor.moveToFirst();
String found =cursor.getString(0);
return found;
}
Hope it Helps!!

public Cursor findstudent(String disc){
SQLiteDatabase sqLiteDatabase = this.getReadableDatabase();
String[] find = new String[]{ col1,col2,col3};//all fields in db in need
String order=col1;
Cursor c=db.query(TABLE_STUDENTS, find, KEY_DISCIPLINE +" = " +disc, null, null, null, order);
c.moveToFirst();
db.close();
return c;
}
In the activity include this:
DataBaseHandler db = new DataBaseHandler(this);
try {
Cursor c = db.displayName(your_disc);
startManagingCursor(c);
if (!c.moveToFirst()) {
System.out.println("!Move " + posnumber);
} else {
String idname = c.getString(c
.getColumnIndex(DataBaseHandler.KEY_NAME));
System.out.println("null:");
System.out.println("Move " + idname);
return true;
}
c.close();
stopManagingCursor(c);
} catch (Exception ex) {
}

Android SQLite Query: Trouble with WHERE clause

Please let me know why my where clause isn't working. I tried using the query instead of rawquery but no luck.
try {
String categoryex = "NAME";
DBHelper dbHelper = new DBHelper(this.getApplicationContext());
MyData = dbHelper.getWritableDatabase();
Cursor c = MyData.rawQuery("SELECT * FROM " + tableName + where Category = '+categoryex'" , null);
if (c != null ) {
if (c.moveToFirst()) {
do {
String firstName = c.getString(c.getColumnIndex("Category"));
String age = c.getString(c.getColumnIndex("Text_Data"));
results.add( firstName + " Directions: " + age);
}while (c.moveToNext());
}
}
} catch (SQLiteException se ) {
Log.e(getClass().getSimpleName(), "Could not create or Open the database");
} finally {
if (MyData != null)
MyData.execSQL("DELETE FROM " + tableName);
MyData.close();
}

try... (you left out a double-quote before where.
Cursor c = MyData.rawQuery("SELECT * FROM " + tableName + " where Category = '" +categoryex + "'" , null);

I think you should use rawQuery in this form:
rawQuery("SELECT * FROM ? where Category = ?", new String[] {tableName, categoryex});
I think it's more secure this way.

Your quotes are buggered:
Cursor c = MyData.rawQuery("SELECT * FROM " + tableName + " where Category = '" + categoryex + "'" , null);
You also should read up on SQL injection attacks.

it will be more easy if you use this technique instead of rawQuery,its easy way change your table name, columns and where conditions accordingly.
public ArrayList<Invitees> getGroupMembers(String group_name) {
ArrayList<Invitees> contacts = new ArrayList<>();
SQLiteDatabase db = this.getReadableDatabase();
String[] projection = {COLUMN_CONTACT, COLUMN_PHONE_NUMBER};
String selection = COLUMN_GROUP_NAME + "=?";
String[] selectionArgs = {group_name};
Cursor cursor = db.query(GROUPS_TABLE_NAME, projection, selection, selectionArgs, null, null, null);
if (cursor.moveToFirst()) {
do {
Invitees invitees = new Invitees();
invitees.setUserName(cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_CONTACT)));
invitees.setInviteePhone(cursor.getString(cursor.getColumnIndexOrThrow(COLUMN_PHONE_NUMBER)));
contacts.add(invitees);
} while (cursor.moveToNext());
}
return contacts;
}