mariadb-connector executemany 抛出 DataError

Question

我正在尝试使用 python-mariadb-connector 实现一些简单的 SQL 插入语句，但无法弄清楚我做错了什么。

数据库如下所示：

SET FOREIGN_KEY_CHECKS = false;

CREATE OR REPLACE TABLE `forums` (
  `id` int(10) unsigned NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE OR REPLACE TABLE `accounts` (
  `id` int(10) unsigned NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE OR REPLACE TABLE `posts` (
  `id` int(10) unsigned NOT NULL,
  `forum_id` int(10) unsigned NOT NULL,
  `account_id` int(10) unsigned NOT NULL,
  PRIMARY KEY (`id`),
  KEY `posts_forum_fk` (`forum_id`),
  KEY `posts_account_fk` (`account_id`),
  CONSTRAINT `posts_account_fk` FOREIGN KEY (`account_id`) REFERENCES `accounts` (`id`),
  CONSTRAINT `posts_forum_fk` FOREIGN KEY (`forum_id`) REFERENCES `forums` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE OR REPLACE TABLE `comments` (
  `id` int(10) unsigned NOT NULL,
  `post_id` int(10) unsigned NOT NULL,
  `account_id` int(10) unsigned NOT NULL,
  `parent_id` int(10) unsigned DEFAULT NULL,
  PRIMARY KEY (`id`),
  KEY `comments_post_fk` (`post_id`),
  KEY `comments_account_fk` (`account_id`),
--  KEY `comments_comments_fk` (`parent_id`),
--  CONSTRAINT `comments_comments_fk` FOREIGN KEY (`parent_id`) REFERENCES `comments` (`id`),
  CONSTRAINT `comments_account_fk` FOREIGN KEY (`account_id`) REFERENCES `accounts` (`id`),
  CONSTRAINT `comments_post_fk` FOREIGN KEY (`post_id`) REFERENCES `posts` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

SET FOREIGN_KEY_CHECKS = true;

插入数据的代码如下：

import mariadb


config = {
    "user": "db_user_name",
    "password": "db_passwd",
    "host": "db_host",
    "port": 3306,
    "database": "db_name"
}


if __name__ == '__main__':
    with mariadb.connect(**config) as conn:
        cur = conn.cursor()
        cur.executemany(
            "INSERT INTO `forums` (`id`) VALUES (?)",
            [(1,), (2,), (3,)]
        )
        cur.executemany(
            "INSERT INTO `accounts` (`id`) VALUES (?)",
            [(1,), (2,), (3,), (4,)]
        )
        cur.executemany(
            "INSERT INTO `posts` (`id`, `forum_id`, `account_id`) VALUES (?, ?, ?)",
            [(6, 3, 1)]
        )
        cur.executemany(
            "INSERT INTO `comments` (`id`, `post_id`, `account_id`, `parent_id`) VALUES (?, ?, ?, ?)",
            [(1, 6, 1, None), (2, 6, 2, 1)]
        ) # exception happens here

执行此操作时，我收到以下错误：

Traceback (most recent call last):
  File ".../db_test.py", line 28, in <module>
    cur.executemany(
mariadb.DatabaseError.DataError: Invalid parameter type at row 2, column 4

我不确定 executemany 是如何实现的，但我认为它应该执行类似于以下 SQL 查询的操作：

INSERT INTO `forums` (`id`) VALUES (1), (2), (3);

INSERT INTO `accounts` (`id`) VALUES (1), (2), (3), (4);

INSERT INTO `posts` (`id`, `forum_id`, `account_id`) VALUES (6, 3, 1);

INSERT INTO `comments` (`id`, `post_id`, `account_id`, `parent_id`)
VALUES (1, 6, 1, NULL), (2, 6, 2, 1);

这对我来说很好......

这是一个错误还是我在这里做错了什么？

Answer 1

我花了一点时间

    cur.executemany(
        "INSERT INTO `comments` (`id`, `post_id`, `account_id`, `parent_id`) VALUES (?, ?, ?, ?)",
        [(1, 6, 1, None), (2, 6, 2, 1)]
    ) 

但是在你的评论表中你有这个限制

CONSTRAINT `comments_comments_fk` FOREIGN KEY (`parent_id`) REFERENCES `comments` (`id`),

在您可以输入 (2, 6, 2, 1) 之前，元组 (1, 6, 1, None) 必须已经提交到数据库中，并且在批量插入中，提交是在所有插入都在数据库中之后进行的，但第一个元组当时不存在

所以如果你这样做，两行都会出现在数据库中（我还在批量插入后提交了所有其他表）：

MAriaDB

 mycursor.execute(
    "INSERT INTO `comments` (`id`, `post_id`, `account_id`, `parent_id`) VALUES (?, ?, ?, ?)",
    (1, 6, 1,None ))
 mydb.commit()    
 mycursor.executemany(
    "INSERT INTO `comments` (`id`, `post_id`, `account_id`, `parent_id`) VALUES (?, ?, ?, ?)",
    [ (2, 6, 2, 1)])    
 mydb.commit()

MySQL

 sql = """INSERT INTO forums (id) VALUES (%s)"""
 val = [("1",), ("2",), ("3",)]
 mycursor.executemany(sql,val)
 mydb.commit()
 mycursor.executemany( 
    "INSERT INTO accounts (id) VALUES (%s)",
    [(1,), (2,), (3,), (4,)]
 )
 mydb.commit()
 mycursor.executemany(
    "INSERT INTO posts (id, forum_id, account_id) VALUES (%s, %s, %s)",
    [(6, 3, 1)]
 )
 mydb.commit()
 mycursor.execute(
    "INSERT INTO `comments` (`id`, `post_id`, `account_id`, `parent_id`) VALUES (%s, %s, %s, %s)",
    (1, 6, 1,None ))
 mydb.commit()    
 mycursor.executemany(
    "INSERT INTO `comments` (`id`, `post_id`, `account_id`, `parent_id`) VALUES (%s, %s, %s, %s)",
    [ (2, 6, 2, 1)])    
 mydb.commit()