为什么我的外键不起作用？

Question

My create table statement:

CREATE TABLE main_table (
    _ID INTEGER PRIMARY KEY AUTOINCREMENT, 
    account_id INTEGER NOT NULL, 
    employee_id INTEGER NOT NULL,
    rating REAL NOT NULL, 
    timestamp LONG NOT NULL, 
    FOREIGN KEY(account_id) REFERENCES ACCOUNTS(_ID), 
    FOREIGN KEY(employee_id) REFERENCES EMPLOYEES(_ID), 
    UNIQUE (account_id, employee_id, timestamp));

However now if I do something like

public void deleteAccount(long accountId) {
    mDatabase.delete(
            ACCOUNTS, 
            _ID + " = ?", 
            new String[]{accountId + ""}
    );
}

Which is basically DELETE FROM ACCOUNTS WHERE _ID = some_id but it isn't cascading through the other tables (employees or main_table) and deleting any records there that link up through the foreign keys.

I do have this code as well:

@Override
public void onConfigure(SQLiteDatabase db){
    db.setForeignKeyConstraintsEnabled(true);
}

Am I misunderstanding how these work? Isn't this what foreign keys are for? Why isn't it cascading?

Answer 1

You have to mention explicitly if you want any cascading

Change the query like below

CREATE TABLE main_table (
    _ID INTEGER PRIMARY KEY AUTOINCREMENT, 
    account_id INTEGER NOT NULL, 
    employee_id INTEGER NOT NULL,
    rating REAL NOT NULL, 
    timestamp LONG NOT NULL, 
    FOREIGN KEY(account_id) REFERENCES ACCOUNTS(_ID) ON DELETE CASCADE,
    FOREIGN KEY(employee_id) REFERENCES EMPLOYEES(_ID) ON DELETE CASCADE,
    UNIQUE (account_id, employee_id, timestamp));