How to Resolve 'UNIQUE Constraint Failed' Error in SQLite on Android?

Why am I encountering a UNIQUE constraint failed error when trying to insert duplicate entries in SQLite on Android?

Logcat output indicates the error: UNIQUE constraint failed: event.id.

The 'UNIQUE constraint failed' error indicates that you are attempting to insert a row with a primary key (or unique field) that already exists. In SQLite, a primary key must be unique for each record. In your case, the error comes from trying to insert a new event with an 'id' that already exists in the 'event' table.

public void addEvent(EventData event) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put(KEY_TITLE,event.getTitle());
    values.put(KEY_DAY_OF_WEEK,event.getDayofWeek());
    values.put(KEY_TOTAL_MINUTES_FROM,event.getFromMinutes());
    values.put(KEY_TOTAL_MINUTES_TO,event.getToMinutes());
    values.put(KEY_LOCATION,event.getLocation());
    // Inserting Row with ID as NULL to auto-generate
    db.insert(TABLE, null, values);
    db.close();
}

Causes

• Attempting to insert a row with an existing primary key value.
• Not auto-generating IDs for new event entries, which leads to conflicts.
• Improper handling of the 'id' field when adding new events.

Solutions

• Ensure that the 'id' for new entries is unique or change it to auto-generate if it is an integer primary key (e.g., consider using `NULL` to auto-increment).
• Verify the database creation code to ensure that the unique constraints are set correctly and prevent duplicates.
• Replace the `id` value being inserted with `null` (if primary key auto-increment behavior is desired).

Mistake: Not auto-generating a unique id for each entry.

Solution: Modify the table to use `INTEGER PRIMARY KEY AUTOINCREMENT` so that the database auto-generates a unique id.

Mistake: Directly inserting a static value for id (like 0) in each event row.

Solution: Avoid providing a specific id; let SQLite handle it by setting id to null in the insert statement.

Mistake: Forgetting to handle a previously existing value in the database when trying to add an event.

Solution: Check existing records with a query before inserting to ensure the id you're trying to insert doesn't already exist.