I’m working on a PostgreSQL PL/pgSQL function that inserts a record into a table or updates it using ON CONFLICT. However, when I run the function, I encounter the following error:

[42702] ERROR: column reference "email" is ambiguous
Detail: It could refer to either a PL/pgSQL variable or a table column.
Where: PL/pgSQL function create_email_verification(text, text, timestamp with time zone) line 3 at RETURN QUERY

Table structure:

CREATE TABLE email_verifications
(
    id          INTEGER DEFAULT nextval('email_verifications_id_seq'::regclass) NOT NULL PRIMARY KEY,
    email       TEXT NOT NULL CONSTRAINT unique_email UNIQUE,
    code        TEXT NOT NULL,
    expires_at  TIMESTAMP WITH TIME ZONE NOT NULL,
    created_at  TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
    verified_at TIMESTAMP WITH TIME ZONE
);

Function:

create function create_email_verification(
    p_email text, 
    p_code text, 
    p_expires_at timestamp with time zone)

returns TABLE(
    id integer, 
    email text, 
    code text, 
    expires_at timestamp with time zone, 
    created_at timestamp with time zone
) language plpgsql
as
$$
BEGIN
    RETURN QUERY
        INSERT INTO email_verifications (email, code, expires_at)
        VALUES (p_email, p_code, p_expires_at)
        ON CONFLICT (email)
        DO UPDATE 
        SET
            code = EXCLUDED.code, 
            expires_at = EXCLUDED.expires_at
        RETURNING 
            email_verifications.id,
            email_verifications.email, 
            email_verifications.code,
            email_verifications.expires_at,
            email_verifications.created_at;
END;
$$;

Bonus information :

Running the same query outside the function works perfectly fine. For example, the following query executes without issues:

INSERT INTO email_verifications (email, code, expires_at)
VALUES ('[email protected]', '123456', NOW())
ON CONFLICT (email)
DO UPDATE 
SET
    code = EXCLUDED.code, 
    expires_at = EXCLUDED.expires_at
RETURNING id, email, code, expires_at, created_at;