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Comparing dates in android sqlite database

I'm comparing two dates in android sqlite database
I stored dates in the format
YYYY-MM-DD
Cursor cursor=db.rawQuery("SELECT * FROM "+tableName+" WHERE SALESDATE BETWEEN '2020-1-01' AND '2020-2-01';",null);
It gives result with dates of month 10, 11 and 12 along with the dates between above specified dates.
I would like to know if it is a bug or is there any mistake in my code.

The problem here is that your date literals are in a non standard (and likely incorrect) format. Appreciate that the following inequality holds true:
'2020-10-01' > '2020-1-01' AND '2020-10-01' < '2020-2-01'
This is true because the text 10 is lexicographically larger than just 1, but also less than 2. To avoid this problem, use proper date literals:
String sql = "SELECT * FROM " + tableName + " WHERE SALESDATE BETWEEN '2020-01-01' AND '2020-02-01';"
Cursor cursor = db.rawQuery(sql, null);
Note that SQLite does not actually have a formal date type. Thus, it is very important to always store your dates in SQLite using a proper ISO format.

You should store your Date as long value in database. Simple new Date().getTime() gives you this value and new Date(long value) returns it back. So you can make such queries easy.
But what I can suggest is to:
Export your table to CSV,
Change the date values to a proper SQLite TimeString and
Re-import the CSV after deleting the original table.
Then, you can run a query like:
SELECT * FROM tableName WHERE SALESDATE BETWEEN '2020-01-01 00:00:00' AND '2020-02-01 23:59:59'

Android: SQLite Getting all records that inserted in last 7 days

Cursor cursor = db.rawQuery("SELECT * FROM expenses WHERE expense_date > (SELECT DATE('now', '-7 day'));", null);
I have this above query to get all records that inserted in last 7 days. But as a result of this query i am getting all the records. The date column of these records is inserted via Android's DatePicker and they are in 30-Jul-2015 format. I guess that's why this query does not work properly. Is there a way to make them consistent to get this query work properly or i am missing out something else ? Any help would be appreciated.

I've never tried using the SQLite built in date functions. Taking a quick look at the SQLite date function documentation here, it would seem that to use them the date needs to be in the format YYYY-MM-DD, which would be why your query is failing.
You can do some string manipulation/formatting before saving to the db and use that format.
Personally, I usually format in that manner but without the dash separators, then a simple less than/greater than comparison can be used, treating the date like a regular number. Of course some conversion back and forth is necessary for display, but for under the hood it works great.
int now = 20150730;
String query = "SELECT * FROM expenses WHERE expense_date > '" + now-7 + "'";

Using select method in SQL

I've added 3 strings of data into a SQL database in android. A fourth string makes up the database, however it is a date:
SimpleDateFormat outputDate = new SimpleDateFormat(yyyy-MM-dd)
Date outputDate = new Date();
When the user enters information to the database, the adding method for the database creates the date, which is added to the database.
My question is, how can I use these imported dates to create a method whereby only the rows in the database that were added on in the last 31 days?
A SELECT method comes to mind through research, but I don't know how to implement it?
Thanks

Presuming your database engine is SQLite, you should try something like that
SELECT * from your_table where julianday('now') - julianday(your_date_field)<=31;
You may be interested in SQLite date functions as well: http://www.sqlite.org/lang_datefunc.html

As long as you ask about Android I assume that the database you use is SQLite. SQLite does not have datatype for date. Thus you have couple of options: store the date in string (like you did) or store the timestamp of the date.
I seriously recommend you to use the second option as it is going to convert your dates in integers and it will be even easier to handle.
Thus when you want to select only events in the last 31 days you can do:
SQLiteDatabase database = helper.getWriteableDatabase();
final long millisIn31Days = 31 * 24 * 60 * 60 * 1000;
String where = "<your-date-column> >= ?"
String [] whereArgs = { String.valueOf(new Date().getTime() - millisIn31Days) };
Cursor cursor =
database.query("<TABLE_NAME>", null, where, whereArgs, null, null, null);
Note that here I write in angular brackets all the values you should actually fill in with the correct constants.
If you, however, want to stick to the string solution, you can still go with string comparison, as long as you specify the date format in correct manner (yours seems to be like that). In the string solution you will need to calculate the date of 31 days ago. You can use the Calendar's class auxiliary methods to achieve that.

SQLite query returns nothing

I have this query in SQLite that I want to return a value based on the date passed. The date is in the database as a String. I know that there is data in the database with that date, but it just returns nothing. I dont know why. When I make the query without comparisson parameters, it returns all the data normally, but using the WHERE clause in the query method, it stops returning. Maybe its just a matter of the SQL syntax. Anyways, here is the statement:
Cursor cursor = db.query(TABLE, new String[] {"_id", "value"}, "current_date = ? ", new String[] {date}, null, null, null);
EDIT
I've made this query in SQLite Database Browser, and it doesn't return any values. Even if its there.
I've seen that this is quite funny and confused. I've tested on Database Browser and also on phone, when I pass the current day, the 'Today' day, it gets the data, but when I pass another day that isnt today, it returns nothing. Very, very weird.
And in Database Browser, I've selected the column that contains the date and it returns only the 'Today' date, even if before there are another dates.

if your date is stored in database in format 'dd-mm-yyyy',then try using it like-
Calendar cal=Calendar.getInstance();
Cursor cursor = db.query(TABLE, new String[] {"_id", "value"}, "date = ? ", String.format("%1$td-%1$tm-%1$tY",cal), null, null, null);
For other formats,please refer http://download.oracle.com/javase/1.5.0/docs/api/java/util/Formatter.html

The column name was 'current_date' and this is a SQLite function name. So it didn't get the other dates, just the current date.

Sorting Sqlite data while display

I have "date"(TEXT) column in db.I want to display dates in ascending order(i.e. group by date).but according to current date.
i.e dates greator or equal than current date should be displayed first and past dates should get appended at last in listview automatically.I used SimpleCursorAdapter to display list.
So how should I do this?

Write the proper query and you should be fine. If you are looking for that particular query as an answer to your question, tag it as sql or sqlite as well.

You can sort data items when you try to query..here a cursor object set with parameters(just an example),the 7th parameter With "ASC" means that the return data will be in ascending oder
cursor cur = yourdata.query(TableName, coloumns, null, null,null, null, table.COLUMN_NAME + " ASC");
if you want an example you can try this code example
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