MySQL的 - 遞增列值基於COUNT

Question

我有這個表：

現在，如果我算在id_racuna列不在NULL使用行：

SELECT COUNT (id_racuna) FROM racuni WHERE id_racuna IS NOT NULL; 

我得到：

所以，如果我在這樣的更新使用此值：

UPDATE racuni AS r1 JOIN racuni AS r2 ON r1.id_interesa = r2.id_interesa 
SET r1.id_racuna = (SELECT COUNT (r2.id_racuna) FROM r2 WHERE r2.id_racuna IS NOT NULL) +1, 
    r1.poslano = curdate() 
WHERE r1.id_interesa = 8; 

我希望得到：

，但我得到一個錯誤：

Table r2 doesn't exist!

我試着欺騙MySQL使用JOIN認爲r1和r2是兩個不同的表，但它不起作用。我見過這種詭計here它在哪裏工作...我錯過了什麼？

---

UPDATE：

我需要使用JOIN因爲如果我寫的只是：

UPDATE racuni 
SET id_racuna = (SELECT COUNT (id_racuna) FROM racuni WHERE id_racuna IS NOT NULL) +1, 
    poslano = curdate() 
WHERE id_interesa = 8; 

我會得到錯誤：

Table 'racuni' is specified twice, both as a target for 'UPDATE' and as a separate source for data

Answer 1

用十字嘗試加入並在其中包裝你的子查詢

UPDATE racuni AS r1 
CROSS JOIN (SELECT COUNT (id_racuna) id_racunacount 
    FROM racuni 
    WHERE id_racuna IS NOT NULL) a 
SET r1.id_racuna = a.id_racunacount + 1, 
    r1.poslano = curdate() 
WHERE r1.id_interesa = 8;