MySQLトリガー：別のテーブルの値を比較します

Question

次のトリガーがあります（mysqli経由でphpを使用して生成）...

DROP TRIGGER IF EXISTS post_queue_insert;
CREATE TRIGGER post_queue_insert AFTER INSERT ON posts
FOR EACH ROW BEGIN
    IF (NEW.post_type != 'revision' AND NEW.post_status != 'auto-draft') THEN
        INSERT INTO event_queue (action_id, action_do, action_key, action_value, action_event, action_timestamp, sync_complete, SITE_ID) VALUES (NEW.ID, 'post', NEW.post_type, NEW.post_status, 'insert', UNIX_TIMESTAMP(now()), 0, 1);
    END IF;
END;

私が理解できないのは、別のテーブルに「post_type」値が存在するかどうか、そしてそれが挿入されていないかどうかを確認する方法です。

?

Answer 1

DROP TRIGGER IF EXISTS post_queue_insert;
CREATE TRIGGER post_queue_insert AFTER INSERT ON posts
FOR EACH ROW BEGIN
    DECLARE found_it INT;
    IF (NEW.post_type != 'revision' AND NEW.post_status != 'auto-draft') THEN
        SELECT COUNT(1) INTO found_it FROM some_other_table
        WHERE post_type = NEW.post_type;
        IF found_it = 0 THEN
            INSERT INTO event_queue (action_id, action_do, action_key, action_value, action_event, action_timestamp, sync_complete, SITE_ID) VALUES (NEW.ID, 'post', NEW.post_type, NEW.post_status, 'insert', UNIX_TIMESTAMP(now()), 0, 1);
        END IF;
    END IF;
END;

fund_it = 0の場合、行にはnew.post_typeに一致する値が含まれていません。

試してみる ！！！

Answer 2

DROP TRIGGER IF EXISTS post_queue_insert;
CREATE TRIGGER post_queue_insert AFTER INSERT ON posts
FOR EACH ROW BEGIN
    IF  ( NEW.post_type != 'revision' 
      AND NEW.post_status != 'auto-draft'
      AND NOT EXISTS
          ( SELECT * 
            FROM other_table
            WHERE post_type = NEW.post_type
          )
        )
    THEN
        INSERT INTO event_queue (action_id, action_do, action_key, action_value, action_event, action_timestamp, sync_complete, SITE_ID) 
        VALUES (NEW.ID, 'post', NEW.post_type, NEW.post_status, 'insert', UNIX_TIMESTAMP(now()), 0, 1);
    END IF;
END;