Question

我试图将一个值从一个表增加到另一个表，但我无法弄清楚正确的语法。有人可以帮我形成一个正确的陈述吗？提前谢谢你：

当前声明：

INSERT INTO points_1_day (nick, amount) 
(SELECT nick, SUM(amount) as increment 
FROM points_log 
WHERE dt >= NOW()-INTERVAL 1 day GROUP BY nick) 
ON DUPLICATE KEY UPDATE 
points_1_day.amount=points_1_day.amount+points_log.increment;

我收到此错误消息：

ERROR 1054 (42S22): Unknown column 'points_log.increment' in 'field list'

Answer 1

ON UPDATE子句中的表达式不能引用SELECT中的列。

但是他们可以引用VALUES(amount)来获取您尝试在给定行上插入的值。

INSERT INTO points_1_day (nick, amount) 
(SELECT nick, SUM(amount) as increment 
FROM points_log 
WHERE dt >= NOW()-INTERVAL 1 day GROUP BY nick) 
ON DUPLICATE KEY UPDATE 
points_1_day.amount=points_1_day.amount+VALUES(amount);

让我测试一下，看看它是否有效......

mysql> insert into points_1_day values (123, 10);
Query OK, 1 row affected (0.01 sec)

mysql> insert into points_log (nick, amount, dt) values (123, 15, NOW());
Query OK, 1 row affected (0.13 sec)

mysql> select * from points_1_day;
+------+--------+
| nick | amount |
+------+--------+
|  123 |     10 |
+------+--------+
1 row in set (0.00 sec)

mysql> INSERT INTO points_1_day (nick, amount)  (SELECT nick, SUM(amount) as increment  
    FROM points_log  WHERE dt >= NOW()-INTERVAL 1 day GROUP BY nick)  
    ON DUPLICATE KEY UPDATE  points_1_day.amount=points_1_day.amount+values(amount);
Query OK, 2 rows affected (0.02 sec)
Records: 1  Duplicates: 1  Warnings: 0

mysql> select * from points_1_day;
+------+--------+
| nick | amount |
+------+--------+
|  123 |     25 |
+------+--------+
1 row in set (0.00 sec)

mysql> INSERT INTO points_1_day (nick, amount)  (SELECT nick, SUM(amount) as increment  
    FROM points_log  WHERE dt >= NOW()-INTERVAL 1 day GROUP BY nick)  
    ON DUPLICATE KEY UPDATE  points_1_day.amount=points_1_day.amount+values(amount);
Query OK, 2 rows affected (0.00 sec)
Records: 1  Duplicates: 1  Warnings: 0

mysql> select * from points_1_day;
+------+--------+
| nick | amount |
+------+--------+
|  123 |     40 |
+------+--------+

是的，似乎有效。

说明：http://dev.mysql.com/doc/refman/5.6/en/insert-on-duplicate.html说：

您可以在VALUES(col_name子句中使用UPDATE）函数引用INSERT语句的INSERT ... ON DUPLICATE KEY UPDATE部分中的列值。换一种说法， VALUES(col_name) in ON DUPLICATE KEY UPDATE子句引用col_name的值将插入，没有发生重复键冲突。这个函数在多行插入中特别有用。 VALUES() 函数仅在INSERT ... UPDATE语句中有意义否则返回NULL。例如：
INSERT INTO table (a,b,c) VALUES (1,2,3),(4,5,6)
  ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);

这也适用于INSERT...SELECT。但VALUES()的参数是您要插入的列名，而不是SELECT中相应列的名称。

INSERT INTO ... ON DUPLICATE KEY UPDATE递增语法

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