I have made a table with user info already stored in it. When the user registers with the id, all the details like username, course are retrieved from the table if the id matches. Now I want to add profile pictures in my user info table. Almost all tutorials on the internet are about saving a photo from your phone into that database and retrieving it. But i don't want that. I would like to add different image into the table for each user, i.e. it should be specific to the user. Now I know a BLOB datatype is used and the images should be converted to bytes. But I don't know where I should store the images, whether in my phone or in my res folder. Or maybe store it on the internet. I am confused. I should mention that this isn't an ideal application, its just a model.
One of the most important factors to consider is the size of the images. If the size is likely to be in excess of say 200k then there is an increasing risk of there being issues not with storing the image in the database but retrieving the image.
Without writing your own alternative of CursorWindow then a CursorWindow (a buffer to hold a sub-group of the rows in a Cursor) is limited to 2M in size (in later versions at some it I believe it was 1M). If a picture is approaching 2MB there is no way that the picture can be retrieved (even without considering space for other columns).
As such, the generally recommended approach is to not store images but store a means of retrieving the image from a file store elsewhere (you've mentioned the res folder, which could be fine but you may need to consider the size of the APK), you could then store the file path in the database.
There's a more comprehensive answer that covers the above including storing small images in the DB and larger images elsewhere (assets folder) here