Develop Reference

How to search in Firestore using multiple fields of documents for android?

I'm using a Firebase Firestore for android to store data. I tried to search data from documents.
My Firestore structure is:
Collection (Products) - Document (Auto Generated ID) - Field (NumberOfPeople,OfferStartDate,OfferEndDate,OfferPrice,Location)
I wrote query for search data on those fields.
CollectionReference collectionOfProducts = db.collection("Products");
collectionOfProducts
.whereEqualTo("Location", location)
.whereGreaterThanOrEqualTo("OfferPrice", offerPrice)
.whereLessThanOrEqualTo("OfferPrice", offerPrice)
.whereGreaterThanOrEqualTo("OfferStartDate", date)
.whereLessThanOrEqualTo("OfferEndDate", date)
.get()
I want search result like this: An offer which is between start date and end date, where offer price is greater than equal or less than equal on give price range. This query is not working in android studio.
How to do this in firestore firebase?

According to the official documentation regarding Cloud Firestore queries, please note that there some query limitations:
In a compound query, range (<, <=, >, >=) and not equals (!=, not-in) comparisons must all filter on the same field.
So a Query object that contains a call to both methods:
.whereGreaterThanOrEqualTo("OfferStartDate", date)
.whereLessThanOrEqualTo("OfferEndDate", date)
Is actually not possible, as "OfferStartDate" and "OfferEndDate" are different properties.
The best solution I can think of is to use only one of these method calls and do the other filtering on the client.
Another possible solution might be to use denormalization and duplicate the data
in certain intervals. In this way, you'll always know the time periods and you'll be able to create the corresponding queries.

To the best of my knowledge, Firestore only lets you use where<Greater/Less>ThanOrEqualTo() and where<Greater/Less>Than() a single field and all other filter operations on other fields can only be whereEqualTo().
Some workarounds for your specific case include -
1) Modifying your query to
collectionOfProducts
.whereGreaterThanOrEqualTo("OfferStartDate", date)
.whereEqualTo("Location", location)
.get()
And then performing the subsequent filtering on the result in your app code.
Alternately, you can perform your filter on "OfferPrice" and "Location" in your query and the remaining filters can be applied to the query result.
2) You can use firebase functions or other server code to write logic that performs customized filtering and fetch the result that way.

i was having same issue with this, but i found a work around that takes sometime to write.
lets say you want to search for a particular keyword(in this case the value of a field inside a document), and you want firebase to search multiple field instead of just looking for 1 particular field.
this is what you want to do.
const searchTerm = document.createElement('input')
db.collection('collection').where('field1', '==', `${searchTerm.value}`)
.get()
.then((snapshot) => {
if(snapshot.size === '0'){
db.collection('collection').where('field2', '==', `${searchTerm.value}`)
.get()
.then((snapshot) => {
if(snapshot.size === 0) {
db.collection......and repeat
}
})
}
})
in summary, the above code is basically telling js to search for the term again with a different field if the result of the previous query is 0. I know this solution might not be able to work if we have a large quantity of fields. But for folks out there that are working with small number fields, this solution might be able to help.
I really do hope firestore one day would allow such feature, but here is the code it worked fine for me.
the problem I have now is to allow search input to be able to search without have me to complete the word. I do currently have an idea how this would be, but just need some time to put together.

How to insert < ' > as a string in SQLite database in android ? [duplicate]

While I was trying the following SQL command , I got sql error.
INSERT INTO exampleTbl VALUES('he doesn't work for me')
where doesn't contain the apostrophe.
What is the way to insert text having ' (apostrophe) into a SQL table.

In SQL, the way to do this is to double the apostrophe:
'he doesn''t work for me'
However, if you are doing this programmatically, you should use an API that accepts parameters and escapes them for you automatically. Programmatically escaping and using string concatenation to assemble a query yourself is a sure way to end up with SQL injection vulnerabilities.

INSERT INTO exampleTbl VALUES('he doesn''t work for me')
If you're adding a record through ASP.NET, you can use the SqlParameter object to pass in values so you don't have to worry about the apostrophe's that users enter in.

$value = "he doesn't work for me";
$new_value = str_replace("'", "''", "$value"); // it looks like " ' " , " ' ' "
INSERT INTO exampleTbl (`column`) VALUES('$new_value')

try this
INSERT INTO exampleTbl VALUES('he doesn''t work for me')

insert into table1 values("sunil''s book",123,99382932938);
use double apostrophe inside of single apostrophe,
it will work

I know the question is aimed at the direct escaping of the apostrophe character but I assume that usually this is going to be triggered by some sort of program providing the input.
What I have done universally in the scripts and programs I have worked with is to substitute it with a ` character when processing the formatting of the text being input.
Now I know that in some cases, the backtick character may in fact be part of what you might be trying to save (such as on a forum like this) but if you're simply saving text input from users it's a possible solution.
Going into the SQL database
$newval=~s/\'/`/g;
Then, when coming back out for display, filtered again like this:
$showval=~s/`/\'/g;
This example was when PERL/CGI is being used but it can apply to PHP and other bases as well. I have found it works well because I think it helps prevent possible injection attempts, because all ' are removed prior to attempting an insertion of a record.

yes, sql server doesn't allow to insert single quote in table field due to the sql injection attack. so we must replace single appostrophe by double while saving.
(he doesn't work for me) must be => (he doesn''t work for me)

you can use backslash '\' if you want to display a single quote in your text.
INSERT INTO exampleTbl VALUES('He doesn(\')t') ;

Compare phone number from database in different condition

I'm developing sms APP and want to receive sms from the specific numbers. But number can be changed sometime with country code as +923201234567 or sometime without country code 03201234567 how I can compare number from database? because don't know in which format number is saved in database(with country code or without country code)
public boolean isMember(String phone, long id){
String query = "SELECT * from members where phone = ? AND active = 1 AND gid = ?";
Cursor c = dbActions.rawQuery(query, new String[]{String.valueOf(phone), String.valueOf(id)});
return c.moveToFirst();
}
Suppose if the number is saved in database without country code 03201234567 then my requirement is to get true if I compare it with country code. +923201234567. Country code could be changed.
PhoneNumberUtils.compare(); is not useful because it not compare with database.

If you can't acquire the correct information always; then you need to look into heuristics.
Meaning: you could write your own comparisons; and when you encounter two numbers like:
03201234567
+923201234567
you can figure: their "tail" is equal; the only difference is that the first one starts with 0 (so no country code) and the second one with +92. So it might be reasonable to declare those two numbers to be equal.
So a "solution" would do things like "normalize" your input (remove all non-digit content; except for leading + signs); and to then make such "tail-bound" comparisons.
If that is "too" fuzzy; I guess then you should step back and describe the requirement that you actually try to resolve here. Why are you comparing numbers; and what do you intend to do with the output of that comparison?!

Normalize all of the phone numbers into the same format before you put them into the database. That way you can just do a normal db search.
The other thing I've done for phone numbers is to convert all letters into the appropriate number, then remove all non digits, then just compare the last 7 digits.

SQlite Language based table selection

just for curious, i got a question!
My app is almost ready.. I have implemented bilingual (English/Tamil) when users select thr preferred language in Settings then whole app gets converted into that language (i used custom Locale). Everything works fine.
My question is, Can we do the same to SQlite database? which fetch data automatically based on locale from table
"country-en"or"country-ta" ? is there any way? i heard that thr is a method SQLiteOpenHelper.onConfigure(setLocale()); to set locale in sqlitedatabase. i want to know how it works!

The method you describe above is not related to language localization for the client. It's related to locale options on the database (for example how to treat string comparisons with accented characters).
Anyway, if you think of it... what does localizing a database mean? You can either localize the structure or the data. Localizing the structure (table names...) doesn't make sens because the user is not aware of it. Localizing the data doesn't make sense either, because that means that if the users changes language settings, next time he uses your app he won't see his data!
If the DB only contains static data and you need to provide a different DB for different languages, you could use localization to lookup for the database filename.

Of course, yes, you can.
When you do your queries, just append "en" or "ta".
Something like "SELECT FROM Country_" + yourLocale + "..." - if you want to use two different tables.
OR you could use one single table with an integer field "Language" and you pass an int (0 = english, 1 = tamil - only for alphabetical order, which is easier to remind)...
Something like "... WHERE ... AND Language = 0"

Sort lists by date?

I have a question. In my app I have saved in my database some lists. Each list has asociated a date in this format 6-June-2011. How can I order these lists by date? I wrote I function like that :
public Cursor getAll(){
return (mDb.rawQuery("SELECT _id, Title, Shop , Data , Budget_allocated ," +
" Budget_spent FROM Lists ORDER BY Data",null));
}
but it doesn't work fine. I think it compare only the day. For example, if I have 31-May-2011 and 6-June-2011, it will say that the first date is after the second date.
It is possible what I am trying to do? Should I modify the date in format like this :6-06-2011?
Thanks..

I don't know anything about android development, but it sounds like your date field is stored as a string rather than a date, is that correct?
If so, you can either:
Change your table so that field is a date (then it should compare correctly)
Or store it in a standard format such that the default string comparison sorts dates correctly. Since string comparison sorts first on first character, second on second character, etc, this would be putting the biggest time difference first, ie. "2011-05-31" (include the zeroes).
(You should be able to convert the field by making a new field, copying the data from the old field into the new field in the correct format, and then deleting the old field and renaming the new one, or more simply if you simply want to change the format of the text. You should be able to do this either from code, or with an "update" query, AFAIK.)

Use a date format as follows...yyyy-MM-dd HH:mm:ss. This is guaranteed to be sortable in ascending or descending order.

If your Data column is not of type datetime there may be an issue. Take a look at this related SO question and answers:
SQL ORDER BY date problem