Python 如何防止重复信息进入mysql数据库？_Python_Mysql_Sql

Python 如何防止重复信息进入mysql数据库？

python mysql sql

Python 如何防止重复信息进入mysql数据库？,python,mysql,sql,Python,Mysql,Sql,在这个程序中，我创建了一个名为mydata的数据库，并创建了一个名为mining的表，我想从中的列表中读取我的姓名和年龄，如果它不在数据库中，请将其保存在数据库中。但我遇到了麻烦，我的程序出现了错误事实上，在编写SQL语法时，如果数据不存在，它会将数据存储在数据库中。我有个问题霉菌代码： import mysql.connector cnx = mysql.connector.connect( host='localhost', user = 'root', pa

在这个程序中，我创建了一个名为mydata的数据库，并创建了一个名为mining的表，我想从中的列表中读取我的姓名和年龄，如果它不在数据库中，请将其保存在数据库中。但我遇到了麻烦，我的程序出现了错误

事实上，在编写SQL语法时，如果数据不存在，它会将数据存储在数据库中。我有个问题

霉菌代码：

import mysql.connector

cnx  = mysql.connector.connect(
    host='localhost',
    user = 'root',
    password = '',
    database = 'mydata'
)

c = cnx.cursor()

list_number = ['mobin','ghanbari',15]


for i in list_number:
    c.execute('INSERT INTO mining VALUES ("%s","%s","%s") WHERE NOT EXISTS (SELECT * FROM mining)'%(i,i,i))

请帮助我解决此问题

您需要为不希望重复的字段添加唯一索引

下面是一个包含3个字段的示例。您可以使用多个字段

mysql> ALTER TABLE mining ADD UNIQUE INDEX(your_field1, your_field2,your_field3);

并使用INSERT IGNORE而不是INSERT。这将防止查询在表中插入相同的数据两次或多次

for i in list_number:
    c.execute('INSERT IGNORE INTO mining VALUES ("%s","%s","%s") )

或执行查询：

SELECT * FROM mining WHERE 
your_field1 = 'mobin' AND 
your_field2 = 'ghanbari' AND 
your_field3 = 15;

在查询之前插入

如果SELECT查询返回某些内容，则不执行INSERT查询。否则执行插入查询。

您需要为不希望重复的字段添加唯一索引

下面是一个包含3个字段的示例。您可以使用多个字段

mysql> ALTER TABLE mining ADD UNIQUE INDEX(your_field1, your_field2,your_field3);

并使用INSERT IGNORE而不是INSERT。这将防止查询在表中插入相同的数据两次或多次

for i in list_number:
    c.execute('INSERT IGNORE INTO mining VALUES ("%s","%s","%s") )

或执行查询：

SELECT * FROM mining WHERE 
your_field1 = 'mobin' AND 
your_field2 = 'ghanbari' AND 
your_field3 = 15;

在查询之前插入

如果SELECT查询返回某些内容，则不执行INSERT查询。否则执行插入查询。

您应该使不需要重复信息的列唯一。这样，当您尝试将重复信息放入其中时，SQL将用Python向您发送一条失败消息

例如，以下表为例：

用户名（唯一）密码我的用户名我的密码

您应该使不需要重复信息的列唯一。这样，当您尝试将重复信息放入其中时，SQL将用Python向您发送一条失败消息

例如，以下表为例：

用户名（唯一）密码我的用户名我的密码访问mysql

$ mysql -u root -p

从命令行在mysql上创建数据库和表作为示例

mysql> CREATE DATABASE sof;

查询正常，1行受影响（0.00秒）

数据库已更改

mysql> CREATE TABLE mining (
    -> id int NOT NULL AUTO_INCREMENT,
    -> lastname varchar(255) NOT NULL,
    -> firstname varchar(255),
    -> age int,
    -> PRIMARY KEY (id)
    -> );

查询正常，0行受影响（0.01秒）

查询正常，0行受影响（0.02秒）记录：0个重复：0个警告：0

mysql> SHOW INDEXES FROM mining;
+--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ 
| Table  | Non_unique | Key_name  | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | 
+--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ 
| mining |          0 | PRIMARY   |            1 | id          | A         |           2 |     NULL | NULL   |      | BTREE      |         |               | 
| mining |          0 | firstname |            1 | firstname   | A         |           2 |     NULL | NULL   | YES  | BTREE      |         |               | 
| mining |          0 | firstname |            2 | lastname    | A         |           2 |     NULL | NULL   |      | BTREE      |         |               | 
| mining |          0 | firstname |            3 | age         | A         |           3 |     NULL | NULL   | YES  | BTREE      |         |               |                     
+--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+                     
4 rows in set (0.00 sec)

请注意字段

非唯一

如果索引可以包含重复项，则为1；如果索引不能包含重复项，则为0

现在是Python脚本：

import mysql.connector

mydb  = mysql.connector.connect(
    host='localhost',
    user = 'root',
    password = '',
    database = 'sof'
)

cursor = mydb.cursor()

listd =[
    {'firstname':'mobin1','lastname':'ghanbari1','age':15},
    {'firstname':'mobin2','lastname':'ghanbari2','age':16},
    {'firstname':'mobin3','lastname':'ghanbari3','age':17},
    {'firstname':'mobin4','lastname':'ghanbari4','age':18}
]

for row in listd:
    sql = "INSERT INTO mining (firstname, lastname , age) VALUES (%s, %s, %s)"
    val = (row['firstname'],row['lastname'], row['age'])

    try:
        cursor.execute(sql, val)
        mydb.commit()
        print(cursor.rowcount, "record inserted for "+row["firstname"])
    except mysql.connector.Error as err:
        print("mysql exception: {}".format(err))
        print(cursor.rowcount, "record inserted for "+row["firstname"])

mysql exception: 1062 (23000): Duplicate entry 'mobin1-ghanbari1-15' for key 'firstname'
-1 record inserted for mobin1
mysql exception: 1062 (23000): Duplicate entry 'mobin2-ghanbari2-16' for key 'firstname'
-1 record inserted for mobin2
mysql exception: 1062 (23000): Duplicate entry 'mobin3-ghanbari3-17' for key 'firstname'
-1 record inserted for mobin3
mysql exception: 1062 (23000): Duplicate entry 'mobin4-ghanbari4-18' for key 'firstname'
-1 record inserted for mobin4
1 record inserted for mobin5
1 record inserted for mobin6
1 record inserted for mobin7

输出：

1 record inserted for mobin1
1 record inserted for mobin2
1 record inserted for mobin3
1 record inserted for mobin4

检查mysql是否插入了记录

mysql> select * from mining;
+----+-----------+-----------+------+
| id | lastname  | firstname | age  |
+----+-----------+-----------+------+
|  1 | ghanbari1 | mobin1    |   15 |
|  2 | ghanbari2 | mobin2    |   16 |
|  3 | ghanbari3 | mobin3    |   17 |
|  4 | ghanbari4 | mobin4    |   18 |
+----+-----------+-----------+------+


4 rows in set (0.00 sec)

在Python脚本列表中添加一些数据*

import mysql.connector mydb = mysql.connector.connect( host='localhost', user = 'root', password = '', database = 'sof' ) cursor = mydb.cursor() listd =[ {'firstname':'mobin1','lastname':'ghanbari1','age':15}, {'firstname':'mobin2','lastname':'ghanbari2','age':16}, {'firstname':'mobin3','lastname':'ghanbari3','age':17}, {'firstname':'mobin4','lastname':'ghanbari4','age':18}, {'firstname':'mobin5','lastname':'ghanbari5','age':19}, {'firstname':'mobin6','lastname':'ghanbari6','age':20}, {'firstname':'mobin7','lastname':'ghanbari7','age':21} ] for row in listd: sql = "INSERT INTO mining (firstname, lastname , age) VALUES (%s, %s, %s)" val = (row['firstname'],row['lastname'], row['age']) try: cursor.execute(sql, val) mydb.commit() print(cursor.rowcount, "record inserted for "+row["firstname"]) except mysql.connector.Error as err: print("mysql exception: {}".format(err)) print(cursor.rowcount, "record inserted for "+row["firstname"])
运行Python脚本
输出：

import mysql.connector mydb = mysql.connector.connect( host='localhost', user = 'root', password = '', database = 'sof' ) cursor = mydb.cursor() listd =[ {'firstname':'mobin1','lastname':'ghanbari1','age':15}, {'firstname':'mobin2','lastname':'ghanbari2','age':16}, {'firstname':'mobin3','lastname':'ghanbari3','age':17}, {'firstname':'mobin4','lastname':'ghanbari4','age':18} ] for row in listd: sql = "INSERT INTO mining (firstname, lastname , age) VALUES (%s, %s, %s)" val = (row['firstname'],row['lastname'], row['age']) try: cursor.execute(sql, val) mydb.commit() print(cursor.rowcount, "record inserted for "+row["firstname"]) except mysql.connector.Error as err: print("mysql exception: {}".format(err)) print(cursor.rowcount, "record inserted for "+row["firstname"])

mysql exception: 1062 (23000): Duplicate entry 'mobin1-ghanbari1-15' for key 'firstname' -1 record inserted for mobin1 mysql exception: 1062 (23000): Duplicate entry 'mobin2-ghanbari2-16' for key 'firstname' -1 record inserted for mobin2 mysql exception: 1062 (23000): Duplicate entry 'mobin3-ghanbari3-17' for key 'firstname' -1 record inserted for mobin3 mysql exception: 1062 (23000): Duplicate entry 'mobin4-ghanbari4-18' for key 'firstname' -1 record inserted for mobin4 1 record inserted for mobin5 1 record inserted for mobin6 1 record inserted for mobin7
检查mysql是否有重复的条目

mysql> select * from mining; +----+-----------+-----------+------+ | id | lastname | firstname | age | +----+-----------+-----------+------+ | 1 | ghanbari1 | mobin1 | 15 | | 2 | ghanbari2 | mobin2 | 16 | | 3 | ghanbari3 | mobin3 | 17 | | 4 | ghanbari4 | mobin4 | 18 | | 13 | ghanbari5 | mobin5 | 19 | | 14 | ghanbari6 | mobin6 | 20 | | 15 | ghanbari7 | mobin7 | 21 | +----+-----------+-----------+------+ 7 rows in set (0.00 sec)
如您所见，表中没有重复的条目。
访问mysql

$ mysql -u root -p
从命令行在mysql上创建数据库和表作为示例

mysql> CREATE DATABASE sof;
查询正常，1行受影响（0.00秒）
数据库已更改

mysql> CREATE TABLE mining ( -> id int NOT NULL AUTO_INCREMENT, -> lastname varchar(255) NOT NULL, -> firstname varchar(255), -> age int, -> PRIMARY KEY (id) -> );
查询正常，0行受影响（0.01秒）
查询正常，0行受影响（0.02秒）记录：0个重复：0个警告：0

mysql> SHOW INDEXES FROM mining; +--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment | +--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ | mining | 0 | PRIMARY | 1 | id | A | 2 | NULL | NULL | | BTREE | | | | mining | 0 | firstname | 1 | firstname | A | 2 | NULL | NULL | YES | BTREE | | | | mining | 0 | firstname | 2 | lastname | A | 2 | NULL | NULL | | BTREE | | | | mining | 0 | firstname | 3 | age | A | 3 | NULL | NULL | YES | BTREE | | | +--------+------------+-----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+ 4 rows in set (0.00 sec)
请注意字段
非唯一
如果索引可以包含重复项，则为1；如果索引不能包含重复项，则为0
现在是Python脚本：

import mysql.connector mydb = mysql.connector.connect( host='localhost', user = 'root', password = '', database = 'sof' ) cursor = mydb.cursor() listd =[ {'firstname':'mobin1','lastname':'ghanbari1','age':15}, {'firstname':'mobin2','lastname':'ghanbari2','age':16}, {'firstname':'mobin3','lastname':'ghanbari3','age':17}, {'firstname':'mobin4','lastname':'ghanbari4','age':18} ] for row in listd: sql = "INSERT INTO mining (firstname, lastname , age) VALUES (%s, %s, %s)" val = (row['firstname'],row['lastname'], row['age']) try: cursor.execute(sql, val) mydb.commit() print(cursor.rowcount, "record inserted for "+row["firstname"]) except mysql.connector.Error as err: print("mysql exception: {}".format(err)) print(cursor.rowcount, "record inserted for "+row["firstname"])

mysql exception: 1062 (23000): Duplicate entry 'mobin1-ghanbari1-15' for key 'firstname' -1 record inserted for mobin1 mysql exception: 1062 (23000): Duplicate entry 'mobin2-ghanbari2-16' for key 'firstname' -1 record inserted for mobin2 mysql exception: 1062 (23000): Duplicate entry 'mobin3-ghanbari3-17' for key 'firstname' -1 record inserted for mobin3 mysql exception: 1062 (23000): Duplicate entry 'mobin4-ghanbari4-18' for key 'firstname' -1 record inserted for mobin4 1 record inserted for mobin5 1 record inserted for mobin6 1 record inserted for mobin7
输出：

1 record inserted for mobin1 1 record inserted for mobin2 1 record inserted for mobin3 1 record inserted for mobin4
检查mysql是否插入了记录

mysql> select * from mining; +----+-----------+-----------+------+ | id | lastname | firstname | age | +----+-----------+-----------+------+ | 1 | ghanbari1 | mobin1 | 15 | | 2 | ghanbari2 | mobin2 | 16 | | 3 | ghanbari3 | mobin3 | 17 | | 4 | ghanbari4 | mobin4 | 18 | +----+-----------+-----------+------+ 4 rows in set (0.00 sec)
在Python脚本列表中添加一些数据*

import mysql.connector mydb = mysql.connector.connect( host='localhost', user = 'root', password = '', database = 'sof' ) cursor = mydb.cursor() listd =[ {'firstname':'mobin1','lastname':'ghanbari1','age':15}, {'firstname':'mobin2','lastname':'ghanbari2','age':16}, {'firstname':'mobin3','lastname':'ghanbari3','age':17}, {'firstname':'mobin4','lastname':'ghanbari4','age':18}, {'firstname':'mobin5','lastname':'ghanbari5','age':19}, {'firstname':'mobin6','lastname':'ghanbari6','age':20}, {'firstname':'mobin7','lastname':'ghanbari7','age':21} ] for row in listd: sql = "INSERT INTO mining (firstname, lastname , age) VALUES (%s, %s, %s)" val = (row['firstname'],row['lastname'], row['age']) try: cursor.execute(sql, val) mydb.commit() print(cursor.rowcount, "record inserted for "+row["firstname"]) except mysql.connector.Error as err: print("mysql exception: {}".format(err)) print(cursor.rowcount, "record inserted for "+row["firstname"])
运行Python脚本
输出：

import mysql.connector mydb = mysql.connector.connect( host='localhost', user = 'root', password = '', database = 'sof' ) cursor = mydb.cursor() listd =[ {'firstname':'mobin1','lastname':'ghanbari1','age':15}, {'firstname':'mobin2','lastname':'ghanbari2','age':16}, {'firstname':'mobin3','lastname':'ghanbari3','age':17}, {'firstname':'mobin4','lastname':'ghanbari4','age':18} ] for row in listd: sql = "INSERT INTO mining (firstname, lastname , age) VALUES (%s, %s, %s)" val = (row['firstname'],row['lastname'], row['age']) try: cursor.execute(sql, val) mydb.commit() print(cursor.rowcount, "record inserted for "+row["firstname"]) except mysql.connector.Error as err: print("mysql exception: {}".format(err)) print(cursor.rowcount, "record inserted for "+row["firstname"])

mysql exception: 1062 (23000): Duplicate entry 'mobin1-ghanbari1-15' for key 'firstname' -1 record inserted for mobin1 mysql exception: 1062 (23000): Duplicate entry 'mobin2-ghanbari2-16' for key 'firstname' -1 record inserted for mobin2 mysql exception: 1062 (23000): Duplicate entry 'mobin3-ghanbari3-17' for key 'firstname' -1 record inserted for mobin3 mysql exception: 1062 (23000): Duplicate entry 'mobin4-ghanbari4-18' for key 'firstname' -1 record inserted for mobin4 1 record inserted for mobin5 1 record inserted for mobin6 1 record inserted for mobin7
检查mysql是否有重复的条目

mysql> select * from mining; +----+-----------+-----------+------+ | id | lastname | firstname | age | +----+-----------+-----------+------+ | 1 | ghanbari1 | mobin1 | 15 | | 2 | ghanbari2 | mobin2 | 16 | | 3 | ghanbari3 | mobin3 | 17 | | 4 | ghanbari4 | mobin4 | 18 | | 13 | ghanbari5 | mobin5 | 19 | | 14 | ghanbari6 | mobin6 | 20 | | 15 | ghanbari7 | mobin7 | 21 | +----+-----------+-----------+------+ 7 rows in set (0.00 sec)

正如您所看到的，表中没有重复的条目。
创建不希望重复的列。数据库中已经有信息。我的意思是，如果列表中的信息不在数据库中，则应将其添加到数据库中。您应向数据库发送查询以插入它，如果返回值不是
true
，这意味着要么查询错误，要么唯一列已经有了该值。否则它将被插入。如果我不明白你的问题，很抱歉。请把你的答案放在答案部分。谢谢。我已经发布了我的答案。请创建一个不希望重复的列。数据库中已经有信息。我的意思是，如果列表中的信息不在数据库中，则应将其添加到数据库中。您应该向数据库发送一个查询以插入它，如果返回值不是
true
，这意味着要么查询错误，要么唯一列已经具有该值。否则它将被插入。如果我不明白你的问题，很抱歉。请把你的答案放在答案部分。谢谢，我已经发布了我的答案。你的答案是错误的。我只是说我如何在数据库中输入不重复的信息。您的解决方案不起作用。我将在新的答案中尽量清晰详细。您的答案是错误的。我只是说我如何在数据库中输入不重复的信息。您的解决方案不起作用，我将在新的答案中尽量清晰和详细。