Ok, I have a database with id column as timestamp
I made an activity list from the db.
I want to manage the db (delete rows) using the list, but the thing is I don't want to
View the whole timestamp, in every row I'll put only the time with some info and
I want to group the list ,as in contacts grouped by alphabet, by the date.
First, how can I make group in an activity list? (Making groups to the output list not the db)
Second, what is the best way to implement this? When user chooses an item and confims delete
I should delete it from the db but I have only patial timestamp...
(My only link to the db is the timestamp - I don't actually know where to store it in the list and I don't want to put it as a string in the text view, do a substring to get it back - is there another way to do this?)
I tried to search tthe web for some examples but I only found a simple ones.
Thnx :-)
?
I think what you're trying to do is create a database of tasks identified by a timestamp. You probably don't want to use a timestamp as a unique ID for the row. Instead, use an integer and qualify it as "PRIMARY KEY" when you create the database.
group the list? I'm not sure why you want to do this in the structure of the database. It's more common to group the list in the output, and leave the db itself in as flat a structure as possible.
Retrieve the primary key when you display a list of tasks. When the user clicks a task, use the primary key to choose the task to delete. You don't have to display the primary key; it serves as a behind-the-scenes "link" between the displayed info and the db row.
http://www.vogella.com/articles/AndroidListView/article.html
I should use cursor adapter for managing db.
And this one for grouping a list:
http://code.google.com/p/android-amazing-listview/
Thnx for the efforts
Related
Looking for a push in the right direction for creating a list of user favourites in Android. I have a list of items from a database which a user can scroll through and add to their favourites so when they log into their account they will be presented with a list of their favourite items. Is it possible to add an array or collection of some sort to the user so when they favourite an item then the primary id is added to some favourites parameter in their account which can be retrieved when they log in?
Sorry if this question is a bit basic, I am still new and am really only making this app to teach myself how to write android apps that use a database.
Thanks in advance!
Since you already have a database. I would add a new table or column to your existing table that would be set to 'true' or 'false' depending on whether or not the item is a user favorite.
This is better than a SharedPreferences because if you store row IDs you now have to manage that information in two places.
Additionally it's easy to get all items or just favorited items using an SQL query.
https://developer.android.com/training/data-storage/sqlite.html
I have in my app a database with two tables : country and rights. Long story short, the db tells me whether a right (there is 10 rights in total) is legal or not in a specific country.
Now, I want the user to be able to search in my db by criterias. I have a layout with checkbox. If the user check a box, it mean he want to see every country in where the right is legal. For exemple, if he check the box "criteria1" and "criteria6", the user want the list of every country where criteria1 and criteria6 are legal, but we don't care wether the other rights are legal or not.
I asigned values to the checkboxs (1 if legal, 0 if illegal, just like in my db) and passes all of them to the activity who display the result of the search.
My problem is, I can't figure out how to search in my database. I need to only get the country where where the selected criters are equal to 1, but I don't know how to formulate my sql request (since I never know which criterias are going to be checked or not). My request need to only be about the criterias who has the value 1.
I had the idea of sending all my values to a function (witch returns a cursor) where I excecute a select statement if the value is equal to one, but I don't know how I could join all the result of my selects in a cursor. I also thought about using "CASE WHEN..." but it doesn't seem to work.
Does anyone have a clue on how I could deal with my search ?
If you need precisions on my problem, please ask.
This guy here (https://www.youtube.com/watch?v=NGRV2qY9ZiU&list=PL200JxfhYIgCrrpH4rCz-uNfBTb5sng1e) has the right idea.
The clip may be a bit slow but it does exactly what you want.
He creates a custom string based on if checkbox is checked and removes it from the string if unchecked.
To get what you want, you need to do a couple of things.
First, create a table with countries as rows, and rights as columns. Add 1 for right is present in country and 0 if not. Get this into an sqlite database (eg import via csv in DB browser for SQLite, free software; don't forget to create the android_metadata table in the sqlite database - search online for this). Import the database in the app (there is plenty of documentation for this online).
Second, change the text inputed in the if/else checkbox part of the script (he writes fruit names, you write for ex. "right1 = 1", or the exact query the checkbox should do on the column right1).
You also need to pay attention to the selection.add and selection.remove (know that selection is an array list which will store all your criteria for search by column).
Third, you need to change the content of his finalSelection (View view).
Delete all he has written and just create two strings:
String final1 = android.text.TextUtils.join(" or ", selection);
String final2 = "select country from table where " + final1;
The string final2 is your key for a cursor with a rawQuery. Just create a cursor in the database and pass the key to it. This can be done easily.
PS the method android.text.TextUtils.join() is amazing :)
You can place the operator of choice there.
If you need more than one operator (and, or etc), you can create different ArrayLists which you fill in the if/else checkbox is filled and join later in the finalSelection.
Oh, btw, if you have too many checkboxes, you will get a warning in the XML file (layout has more than 80 views is bad for performance).
In order to get around that, you need to get to know grid views a bit better. After reading a few tutorials on the basic use of GridViews, a good start for checkboxes inside them is here.
It may seem like a lot, but you need to learn to use holders to get information out of the getView of the modified BaseAdapter.
If you want to understand it better, follow the arrPath.
It is a String[] filled with all the paths of images found inside the cursor (string values from the dataColumnIndex, which contains paths of images).
Within the onClick() listener of the Button, from the arrPath he extracts only the rows of the cursor that were selected by checkbox click (thumbnailsselection[i] is a boolean - with a value TRUE/FALSE for each row in the cursor).
The selected paths are placed in the selectImages String, separated by OR.
I put my data in 3 tables(Links, Images and PDF)
each table has columns(university, faculty, grade, and description,...)
I want to retrieve description column in the 3 tables.
where university, faculty, and grade equal to certain values.
and sort them with creation date.
how can I perform that query in parse?
I'm not familiar with Android, but I'm pretty sure Parse does not support "Join" in the way a SQL database does. You could nest the queries, performing the next one in the previous one's completion block.
However, if you regularly want to get data from those 3 tables, I'd suggest you make it 1 table instead, with a column "Content" instead of Link/Img/PDF. Images and PDFs would probably be stored as PFFiles anyway, and you can put link as either its own string column or putting it in a file. You could also add a column "type" if you want to be able to query a specific type, or just keep track of which columns contains which data.
Then you could query the "Content" class, on the keys you want.
I think this link might help you
https://parse.com/docs/js/guide#relations and it is quite simple and nicely explained . You can't do it directly in the database, though.
I am trying to populate ListView from SQLite database.
I have this table:
CREATE TABLE meaning(
key TEXT,
value TEXT,
entries BLOB);
And created this index for column key:
CREATE INDEX index_key on meaning(key);
I am using this query to get needed data from database:
SELECT rowid AS _id, value, entries
FROM meaning
WHERE key
LIKE 'dog%'
ORDER BY key
LIMIT 100
Result is coming in 510ms. This is quite slow for incremental search. Is it possible to populate ListView part by part so that when user scrolls down ListView, other part of data will be shown?
Yes, you can load the data in parts so that the user sees the result set only as the view is being swiped down. Follow the example at this location http://www.avocarrot.com/blog/implement-infinitely-scrolling-list-android/ to see how it's done.
Basically all you're doing is listening to the scroll change and then adding more results from a loader. Don't forget that once the results have been added to the underlying list, they are not removed simply because you swipe back up. From that point on, they will always be there.
I have an application that uses a pre-polulated database to list events. The app allows people to save these events to their favorites by setting a '1' to the column isFavorite. Then the user can view only a list of 'favorited' events which searches for all rows that have isFavorite = 1.
If any changes happen to the events or I need to add more to the list, I have to make those changes and then push the update to the app which completely writes over the table, clearing out their favorites.
Is there any way that I can, on upgrade, save a list of id's of all the events that they have set to their favorites, then after the new database has been loaded, to set all id's in that list to 1 so the user doesn't lose their favorited data?
If there are any other better solutions to this problem I would really appreciate it, this has been the biggest hurdle for me so far.
I guess, you have a SQLiteOpenHelper-class? This class must be extended and then provides two functions: onCreate (which is called when the Database is queried and it doesn't exist (Normally creates your Database in the first place)) and onUpdate (which is queried when the Database structure should be updated).
The onUpdate-method has an SQLiteDatabase-Object parameter, which is your Database. You can then Query the information you need, save them and then create the new Database-tables. After that, you can insert your saved data back into the Database.
Can't you cope with thus in your DB design? Have a user favourites table that holds id's. So long as these id's don't change upgrade won't affect it surely?
One possible solution is backing up part or all of your database to restore at a later time. I found this guide quite handy http://www.screaming-penguin.com/node/7749
Alternatively, you may save their favorites as a SharedPreferences. http://developer.android.com/reference/android/content/SharedPreferences.html for more information on that.