counting rows of sqlite INSERT SELECT

Question

I have two sqlite tables, where one table has a foreign key of the other.

CREATE TABLE a (id INTEGER PRIMARY KEY NOT NULL, value TEXT UNIQUE NOT NULL);
CREATE TABLE b (id INTEGER PRIMARY KEY NOT NULL, a INTEGER REFERENCES a (id) NOT NULL, value TEXT NOT NULL);

I am doing an INSERT with a SELECT into b.

INSERT INTO b (a, value) SELECT ?value, a.id FROM a WHERE a.value == ?a;

How do I know weather a row was inserted into b or not? Doing a SELECT for the just inserted values and checking weather they exist, seems rather inefficient.

Answer 1

I hope the changes() function can help you.

The changes() function returns the number of database rows that were changed or inserted or deleted by the most recently completed INSERT, DELETE, or UPDATE statement, exclusive of statements in lower-level triggers. The changes() SQL function is a wrapper around the sqlite3_changes() C/C++ function and hence follows the same rules for counting changes.

So changes() returns 1 if a row was inserted and 0 otherwise.