MySQL IF表達式返回錯誤

Question

SELECT last_played INTO @lp FROM sr WHERE creator_id = 1 AND playing = 1 LIMIT 1; 
SELECT stream_id INTO @sid FROM account_stream WHERE owner = 1 AND enabled = 1 LIMIT 1; 
UPDATE sr SET last_played = 1412259166 WHERE creator_id = 1 AND playing = 1 LIMIT 1; 
IF @lp != NULL THEN UPDATE streams SET duration = (duration + (1412259166 - @lp)) WHERE id = @sid LIMIT 1; END IF; 

我在做什麼：當@lp返回一些東西（換句話說，當在第一個查詢中播放時是1），然後執行最後的更新流查詢。

我得到這個錯誤在phpMyAdmin壽：

1064 - 你在你的SQL語法錯誤;檢查與您的MySQL服務器版本相對應的手冊，以便在'IF @lp！= 0 THEN UPDATE streams SET duration =（duration +（1412259166 - @lp））'附近使用正確的語法。第1行的W'

I從來沒有與MySQL的條件如果之前，所以，任何人都可以請幫助我嗎？

Answer 1

UPDATE streams SET duration = (duration + (1412259166 - @lp)) 
WHERE @lp IS NOT NULL AND id = @sid