Question

是否可以使用mysqldb插入表格并投射自动增量值？

例如：

def __init__(self):
  self.connection = MySQLdb.connect(self.v3_host, self.v3_user, self.v3_password, self.v3_database)
  self.cursor = self.connection.cursor()

def insert(self, query):
  try:
    self.cursor.execute(query)
    self.connection.commit()
  except:
    self.connection.rollback()

db3 = DatabaseV3()
insert = """INSERT INTO user_avatars (id, user_id, file_id) VALUES (..."""
db3.insert(insert)

ID是来自数据库的自动增量值，但是如果我希望它强制插入列的特定值而不实际更改列呢？

Answer 1

仅仅因为它的自动递增，并不意味着你不能覆盖这个值：

INSERT INTO user_avatars (id, user_id, file_id) VALUES (23, 42, 56)

您只需要确保没有使用该值，否则您将从数据库中获得异常：

mysql> create table foo (id INT AUTO_INCREMENT PRIMARY KEY, bar INT);
Query OK, 0 rows affected (0.10 sec)

mysql> insert into foo values (12,1), (23,1);
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0

mysql> select * from foo;

+----+------+
| id | bar  |
+----+------+
| 12 |    1 |
| 23 |    1 |
+----+------+
2 rows in set (0.00 sec)

mysql> insert into foo (bar) values (13);
Query OK, 1 row affected (0.01 sec)

mysql> select * from foo;
+----+------+
| id | bar  |
+----+------+
| 12 |    1 |
| 23 |    1 |
| 24 |   13 |
+----+------+
3 rows in set (0.00 sec)
mysql> insert into foo values (12, 2);
ERROR 1062 (23000): Duplicate entry '12' for key 'PRIMARY'

如果您愿意，也可以更改主键的值：

mysql> update foo set id = 13 where id = 12 limit 1;
Query OK, 1 row affected (0.06 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from foo;
+----+------+
| id | bar  |
+----+------+
| 13 |    1 |
| 23 |    1 |
| 24 |   13 |
+----+------+
3 rows in set (0.00 sec)

Python MySQLdb插入主键

1 个答案: