错误代码：1265。列的数据被截断

Question

我有一个名为 pt_products 的表，其中包含以下字段

id  int(11) NO  PRI     auto_increment
merchant    varchar(64) NO  MUL     
filename    varchar(255)    NO  MUL     
name    varchar(255)    NO  MUL     
description text    NO          
image_url   varchar(255)    NO          
buy_url text    NO          
price   decimal(10,2)   NO      0.00    
category    varchar(64) NO  MUL     
brand   varchar(64) NO  MUL     
rating  int(11) NO      0   
reviews int(11) NO      0   
search_name varchar(255)    NO  MUL     
normalised_name varchar(255)    NO  MUL     
original_name   varchar(255)    NO          
voucher_code    varchar(255)    NO          
categoryid  int(11) NO      0   
dupe_hash   varchar(32) NO  UNI     
ean varchar(255)    NO  MUL 0   
asin    char(10)    NO          
Amazon_Top_Sales    bigint(7)   NO      0   
availability    varchar(255)    NO          
mpn varchar(255)    NO  MUL     
delivery_cost   decimal(10,2)   NO      0.00    

我创建一个新表

create table graph (
    id int primary key auto_increment,
    ean varchar(255) unsigned not null,
    avg_price decimal(10,2) not null,
   created_at timestamp default current_timestamp
);

然后，我想将表 pt_products 中的字段插入到上面创建的图表中

insert into graph(ean, avg_price)
select ean, avg(price) avg_price
from pt_products
group by ean;

那是我得到错误的时候

4566 row(s) affected, 64 warning(s): 1265 Data truncated for column 'avg_price' at row 8438 1265 Data truncated for column 'avg_price' at row 8439 1265 Data truncated for column 'avg_price' at row 8440 1265 Data truncated for column 'avg_price' at row 9235 1265 Data truncated for column 'avg_price' at row 9300 1265 Data truncated for column 'avg_price' at row 9333 1265 Data truncated for column 'avg_price' at row 9337 1265 Data truncated for column 'avg_price' at row 9338 1265 Data truncated for column 'avg_price' at row 9339 1265 Data truncated for column 'avg_price' at row 9341 1265 Data truncated for column 'avg_price' at row 9369 1265 Data truncated for column 'avg_price' at row 9370 1265 Data truncated for column 'avg_price' at row 9371 1265 Data truncated for column 'avg_price' at row 9375 1265 Data truncated for column 'avg_price' at row 9376 1265 Data truncated for column 'avg_price' at row 9382 1265 Data truncated for column 'avg_price' at row 9385 1265 Data truncated for column 'avg_price' at row 9386 1265 Data truncated for column 'avg_price' at row 9389 1265 Data truncated for column 'avg_price' at row 9393 1265 Data truncated for column 'avg_price' at row 9401 1265 Data truncated for column 'avg_price' at row 9459 1265 Data truncated for column 'avg_price' at row 9460 1265 Data truncated for column 'avg_price' at row 9532 1265 Data truncated for column 'avg_price' at row 9596 1265 Data truncated for column 'avg_price' at row 9608 1265 Data truncated for column 'avg_price' at row 9617 1265 Data truncated for column 'avg_price' at row 9618 1265 Data truncated for column 'avg_price' at row 9626 1265 Data truncated for column 'avg_price' at row 9669 1265 Data truncated for column 'avg_price' at row 9675 1265 Data truncated for column 'avg_price' at row 9677 1265 Data truncated for column 'avg_price' at row 9678 1265 Data truncated for column 'avg_price' at row 9680 1265 Data truncated for column 'avg_price' at row 9683 1265 Data truncated for column 'avg_price' at row 9695 1265 Data truncated for column 'avg_price' at row 9710 1265 Data truncated for column 'avg_price' at row 9711 1265 Data truncated for column 'avg_price' at row 9739 1265 Data truncated for column 'avg_price' at row 9759 1265 Data truncated for column 'avg_price' at row 9760 1265 Data truncated for column 'avg_price' at row 9768 1265 Data truncated for column 'avg_price' at row 9775 1265 Data truncated for column 'avg_price' at row 9777 1265 Data truncated for column 'avg_price' at row 9780 1265 Data truncated for column 'avg_price' at row 9789 1265 Data truncated for column 'avg_price' at row 9797 1265 Data truncated for column 'avg_price' at row 9829 1265 Data truncated for column 'avg_price' at row 9856 1265 Data truncated for column 'avg_price' at row 9874 1265 Data truncated for column 'avg_price' at row 9897 1265 Data truncated for column 'avg_price' at row 9902 1265 Data truncated for column 'avg_price' at row 9917 1265 Data truncated for column 'avg_price' at row 9936 1265 Data truncated for column 'avg_price' at row 9949 1265 Data truncated for column 'avg_price' at row 9961 1265 Data truncated for column 'avg_price' at row 9976 1265 Data truncated for column 'avg_price' at row 9985 1265 Data truncated for column 'avg_price' at row 9991 1265 Data truncated for column 'avg_price' at row 9995 1265 Data truncated for column 'avg_price' at row 10003 1265 Data truncated for column 'avg_price' at row 10005 1265 Data truncated for column 'avg_price' at row 10007 1265 Data truncated for column 'avg_price' at row 10010 Records: 4566  Duplicates: 0  Warnings: 215

价格字段是

price   decimal(10,2)

和目标表图表中的 avg_price 相同。

avg_price decimal(10,2) not null,

数据不应该在那里吗？

我尝试将 avg_price 从图表更改为小数 (20,4)，但没有成功。

我真的看不到发生了什么。

示例tests here

谢谢

Answer 1

NUMERIC(10,2) 列上的 AVG() 函数（如您的 price 列）生成类型为 NUMERIC(14,6) 的结果。

演示：

mysql> create table t ( price numeric(10,2));

mysql> create table t2 as select avg(price) avg_price from t;

mysql> show create table t2\G
*************************** 1. row ***************************
       Table: t2
Create Table: CREATE TABLE `t2` (
  `avg_price` decimal(14,6) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4

（NUMERIC 和 DECIMAL 是同义词。）

当您尝试将具有六位刻度的值填充到具有两位刻度的列中时，MySQL 必须假设它可能在此过程中会丢失一些信息。

演示：存储具有两位数的数字是可以的，并且不会导致警告：

mysql> insert into t select 3.14;
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

但规模更大的数字会导致警告：

mysql> insert into t select 3.1415927;
Query OK, 1 row affected, 1 warning (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 1

mysql> show warnings;
+-------+------+--------------------------------------------+
| Level | Code | Message                                    |
+-------+------+--------------------------------------------+
| Note  | 1265 | Data truncated for column 'price' at row 1 |
+-------+------+--------------------------------------------+
1 row in set (0.00 sec)

您可以将数值表达式显式转换为相同的数据类型，以避免出现警告：

mysql> insert into t select cast(3.1415927 as decimal(10,2));
Query OK, 1 row affected (0.01 sec)
Records: 1  Duplicates: 0  Warnings: 0

Answer 2

你的选择是错误的。 为：

select ean, avg(price) avg_price
from pt_products
group by ean;

你得到：

ean     avg_price
10086100372     929.500000
10343943704     3697.333333
10343943707     3834.000000
10343943708     9999.990000
884116311874    10499.500000
884116311875    10499.500000
884116321378    14789.000000

然后就被打败了。

您需要将平均数字四舍五入到 2 位，因为您使用 2 位小数。

select ean, round(avg(price),2) avg_price

这会给你：

10086100372     929.50
10343943704     3697.33
10343943707     3834.00
10343943708     9999.99
884116311874    10499.50
884116311875    10499.50
884116321378    14789.00