从您对所需功能的描述来看，您似乎希望 poll_id 和 ip_address一个唯一的对或唯一的复合.

From your description on the desired functionality, it would seem that you want poll_id and ip_address to be a unique pair or compound unique.

CREATE TABLE tbl_poll ( 
    id         INTEGER PRIMARY KEY AUTOINCREMENT,
    poll_id    STRING NOT NULL,
    ip_address STRING NOT NULL,
    opt        STRING NULL,
    CONSTRAINT 'unique_vote_per_poll_per_ip_address' UNIQUE ( poll_id, ip_address )  ON CONFLICT REPLACE 
);