I am building an android app project with SQLite DB.
I got stuck on One-To-Many RelationShip.
This is One
private static final String createTableOrders =
"CREATE TABLE " + TABLE_ORDER + "("
+ KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
...
+ KEY_COLUMN_FORMATS + " INTEGER REFERENCES " + TABLE_FORMATS + "(" + KEY_ID + ")"
+ ");";
This is Many
private static final String createTableFormats =
"CREATE TABLE " + TABLE_FORMATS + "("
+ KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT,"
...
+ ");";
My problems is with set/get methods. Lets say that I would need to get list of ids of all Formats that are in one Order. I guess same thing goes for set method.
I tried to find this kind of question on SO but most of the question were just for SQL part.
P.S. Spent 3 hours trying to make it by myself but the only thing I got to was using GSON to code list of ids into String but it was just a dead-end.
EDIT: I need to get that information inside the code.
P.S.S I have been doing this for 18 hours so sorry if this is uber-stupid question.
A one-to-many relationship requires the foreign key column in the "many" table:
In SQL:
CREATE TABLE Orders (
ID PRIMARY KEY
);
CREATE TABLE Formats (
ID PRIMARY KEY,
OrderID REFERENCES Orders(ID)
);
To get all formats belonging to an order, you just look up rows with the ID of that order:
SELECT * FROM Formats WHERE OrderID = ?
In Java:
Cursor cursor = db.query(TABLE_FORMATS,
new String[] { whatever columns you need },
"OrderID = " + orderID,
null, null, null, null, null);
while (cursor.moveToNext()) {
// read one order from the cursor
}
cursor.close();