MySQL的 - 递增列值基于COUNT

Question

我有这个表：

现在，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，如果我在这样的更新使用此值：

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：

，但我得到一个错误：

Table r2 doesn't exist!

我试着欺骗MySQL使用JOIN认为r1和r2是两个不同的表，但它不起作用。我见过这种诡计here它在哪里工作...我错过了什么？

---

UPDATE：

我需要使用JOIN因为如果我写的只是：

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

我会得到错误：

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

Answer 1

用十字尝试加入并在其中包装你的子查询

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;