Develop Reference

How to write a sqlite query to get specific data?

I want to get the first name, middle name and last name of a student whose userid is used for login. I have written this particular piece of code but it stops my application.
I have used both the ways like database.query() and .rawquery() also.
Cursor studentData(String userId) {
SQLiteDatabase db = getWritableDatabase();
Cursor cursor = db.query(studentTable, new String[] { "First_Name", "Middle_Name", "Last_Name"}, "User_ID=?", new String[] { userId }, null, null, null, null);
// Cursor cursor = db.rawQuery("select First_Name, Middle_Name, Last_Name from Student_Table where User_ID =?", new String[]{userId});
String data = cursor.getString(cursor.getColumnIndex("First_Name"));
db.close();
return cursor;
}
I should get whole name in the string.

You have a number of issues.
Attempting to use String data = cursor.getString(cursor.getColumnIndex("First_Name"));,
will result in an error because you have not moved the cursor beyond BEFORE THE FIRST ROW and the attempt to access the row -1 will result in an exception (the likely issue you have encountered).
you can use various move??? methods e.g. moveToFirst, moveToNext (the 2 most common), moveToLast, moveToPosition.
Most of the Cursor move??? methods return true if the move could be made, else false.
You CANNOT close the database and then access the Cursor (this would happen if the issue above was resolved)
The Cursor buffers rows and then ONLY when required.
That is The Cursor is when returned from the query method (or rawQuery) at a position of BEFORE THE FIRST ROW (-1), it's only when an attempt is made to move through the Cursor that the CursorWindow (the buffer) is filled (getCount() included) and the actual data obtained. So the database MUST be open.
If you want a single String, the full name, then you could use :-
String studentData(String userId) { //<<<<<<<<<< returns the string rather than the Cursor
SQLiteDatabase db = getWritableDatabase();
String rv = "NO NAME FOUND"; //<<<<<<<<<< value returned if no row is located
Cursor cursor = db.query(studentTable, new String[] { "First_Name", "Middle_Name", "Last_Name"}, "User_ID=?", new String[] { userId }, null, null, null, null);
if (cursor.modeToFirst()) {
String rv =
cursor.getString(cursor.getColumnIndex("First_Name")) +
" " +
cursor.getString(cursor.getColumnIndex("Middle_Name")) +
" " +
cursor.getString(cursor.getColumnIndex("Last_Name"));
}
cursor.close(); //<<<<<<<<<< should close all cursors when done with them
db.close(); //<<<<<<<<<< not required but would result in an exception if returning a Cursor
return rv;
}
Or alternately :-
String studentData(String userId) { //<<<<<<<<<< returns the string rather than the Cursor
SQLiteDatabase db = getWritableDatabase();
String rv = "NO NAME FOUND"; //<<<<<<<<<< value returned if no row is located
Cursor cursor = db.query(studentTable, new String[] { "First_Name"||" "||"Middle_Name"||" "||"Last_Name" AS fullname}, "User_ID=?", new String[] { userId }, null, null, null, null);
if (cursor.modeToFirst()) {
String rv =
cursor.getString(cursor.getColumnIndex("fullname"));
}
cursor.close(); //<<<<<<<<<< should close all cursors when done with them
db.close(); //<<<<<<<<<< not required but would result in an exception if returning a Cursor
return rv;
}
the underlying query being SELECT First_Name||" "||Middle_Name||" "||LastName AS fullname FROM student_table; so you concatenate the names as part of the query which returns just one dynamically created column named fullname.

Why returning values from sqlite returns an empty array

Im using the following code to add values to db.
public void addComplianceAcceptability(ComplianceAcceptability complianceAcceptability) {
SQLiteDatabase sqLiteDatabase = this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(KEY_ID, complianceAcceptability.getId());
contentValues.put(KEY_COUNTRY_ID, complianceAcceptability.getCountryId());
contentValues.put(KEY_DOMAIN_ID, complianceAcceptability.getDomainId());
contentValues.put(KEY_UNIT_ID, complianceAcceptability.getUnitId());
contentValues.put(KEY_COMPLIANCE_ID, complianceAcceptability.getComplianceId());
contentValues.put(KEY_COMPLIANCE_NAME, complianceAcceptability.getCompliancenName());
contentValues.put(KEY_COMPLIANCE_FREQUENCY, complianceAcceptability.getComplianceFrequency());
contentValues.put(KEY_COMPLIANCE_APPLICABLE, complianceAcceptability.getComplianceApplicable());
contentValues.put(KEY_COMPLIANCE_OPTED, complianceAcceptability.getComplianceOpted());
sqLiteDatabase.insert(TABLE_COMPLIANCE_ACCEPTABILITY, null, contentValues);
sqLiteDatabase.close();
}
Imm trying to access the values using the following code,
public List<ComplianceAcceptability> getAllAcceptability() {
List<ComplianceAcceptability> complianceAcceptabilityList = new ArrayList<>();
String selectQuery = "SELECT * FROM " + TABLE_COMPLIANCE_ACCEPTABILITY;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
ComplianceAcceptability complianceAcceptability = new ComplianceAcceptability();
complianceAcceptability.setId(Integer.parseInt(cursor.getString(0)));
complianceAcceptability.setCountryId(cursor.getString(1));
complianceAcceptability.setDomainId(cursor.getString(2));
complianceAcceptability.setUnitId(cursor.getString(3));
complianceAcceptability.setComplianceId(cursor.getString(4));
complianceAcceptability.setCompliancenName(cursor.getString(5));
complianceAcceptability.setComplianceFrequency(cursor.getString(6));
complianceAcceptability.setComplianceApplicable(cursor.getString(7));
complianceAcceptability.setComplianceOpted(cursor.getString(8));
} while (cursor.moveToNext());
}
return complianceAcceptabilityList;
}
The problem is that it returns an empty array. But when I try to print the contentValues within addComplianceStatus, it of course prints the array of all values.

You never add anything to complianceAcceptabilityList. You just assign it once, then do nothing to it before returning it. Maybe you want to add complianceAcceptability into it at each iteration through the cursor?

Here you are not adding the complianceAcceptability object to the complianceAcceptabilityList, your modified code:
if (cursor.moveToFirst()) {
do {
ComplianceAcceptability complianceAcceptability = new ComplianceAcceptability();
complianceAcceptability.setId(Integer.parseInt(cursor.getString(0)));
complianceAcceptability.setCountryId(cursor.getString(1));
complianceAcceptability.setDomainId(cursor.getString(2));
complianceAcceptability.setUnitId(cursor.getString(3));
complianceAcceptability.setComplianceId(cursor.getString(4));
complianceAcceptability.setCompliancenName(cursor.getString(5));
complianceAcceptability.setComplianceFrequency(cursor.getString(6));
complianceAcceptability.setComplianceApplicable(cursor.getString(7));
complianceAcceptability.setComplianceOpted(cursor.getString(8));
complianceAcceptabilityList.add(complianceAcceptability);
} while (cursor.moveToNext());
}

How to retrieve data on specific date in Android database

I have a column in database that stores the date in the format(yyyy-MM-dd).I don't know where is the error in my code but it does nothing (even though the file exists) when I run the program.What should be the sql statement to retrieve data from database on specific date?Any help would be appreciated.Thank you.
public ArrayList<Filenames> GetByDate(String dates) {
try {
filename_list.clear();
String q="SELECT * FROM "+ TABLE_FILENAMES + " WHERE date=" + dates;
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(q,null);
if (cursor.moveToFirst()) {
do {
Filenames contact = new Filenames();
contact.setID(Integer.parseInt(cursor.getString(0)));
contact.setDate(cursor.getString(1));
contact.setName(cursor.getString(2));
filename_list.add(contact);
} while (cursor.moveToNext());
}
// return contact list
cursor.close();
db.close();
return filename_list;

try like that.
String q = "SELECT * FROM " + TABLE_FILENAMES + " WHERE date = '" + dates + "'";
I hope this will help you...!

How to check the value already excists or not in sqlite db in android?

In my application I am saving a bill number in SQLite database. Before I add a new bill number how to check if the bill number exists in the DB.
My main class code is,
String bill_no_excist_or_not = db.billno_exist_or_not(""+et_bill_number.getText().toString());
Log.v("Bill No", ""+bill_no_excist_or_not);
My DB Code,
String billno_exist_or_not(String bill_number){
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(TABLE_BILL_DETAILS, new String[] { KEY_BILL_NUMBER }, KEY_BILL_NUMBER + "=?"
+ new String[] { bill_number }, null, null, null, null);
//after this i don't know how to return the values
return bill_number;
}
I don't know how to check the values which is already available or not in DB. Can any one know please help me to solve this problem.

Here is the function that helps you to find whether the value is available in database or not.
Here please replace your query with my query..
public int isUserAvailable(int userId)
{
int number = 0;
Cursor c = null;
try
{
c = db.rawQuery("select user_id from user_table where user_id = ?", new String[] {String.valueOf(userId)});
if(c.getCount() != 0)
number = c.getCount();
}
catch(Exception e) {
e.printStackTrace();
} finally {
if(c!=null) c.close();
}
return number;
}

Make your KEY_BILL_NUMBER column in your table UNIQUE and you can just insert using insertWithOnConflict with the flag SQLiteDatabase.CONFLICT_IGNORE

row id from database

i am trying to do a query of my database for a string lets call it "Test" and then find out what row that particular string is in and save that number to use. I thought i had this figured out before but now it is not working for some reason and i get an error saying no such column "Test".
here is my code
public String getRow(String value){
ContactDB db = new ContactDB(this);
db.open();
Cursor curs = db.getId(value);
String test = curs.getString(curs.getColumnIndex(db.NAME));
curs.close();
Log.v("Contact", "Row ID: " + test);
db.close();
return test;
}
"Test" is sent into that as value
this is in my database
//---retrieve contact id---
public Cursor getId(String where){
Cursor c = db.query(DATABASE_TABLE, new String[] {ID},where,null,null,null,null);
if (c != null)
c.moveToFirst();
return c;
}
i dont remember changing anything from when i first tested it so i dont know why it wont work now

There are 2 errors that i could notice:
In the query
Cursor c = db.query(DATABASE_TABLE, new String[] {ID},where,null,null,null,null);
only the ID column is selected whereas you are trying to fetch details for column NAME
String test = curs.getString(curs.getColumnIndex(db.NAME));
include the name column as well in the select clause : something like
Cursor c = db.query(DATABASE_TABLE, new String[] {ID,NAME},where,null,null,null,null);
In the where clause you need to write the condition string excluding "where"
in your case String where contains value "Test". Hence the filter condition should be as
String whereClasue = NAME + " = '" + where + "'";
The query should be something like this:
public Cursor getId(String where){
Cursor c = db.query(DATABASE_TABLE, new String[] {ID,PHONE_NUMBER,NAME},NAME + " = '" + where + "'",null,null,null,null);
if (c != null)
c.moveToFirst();
return c;
}