To connect to the MySQL database, first install the pymysql library, use pip or conda to install; then establish a connection through the connect() method and create a cursor; then execute SQL statements and get the results; finally close the connection or use the context manager to automatically release the resources. Frequently asked questions include username and password errors, host IP errors, firewall restrictions, and database services not running. You can check the configuration and print exception information. It is recommended to use utf8mb4 to avoid garbled code for character sets.
Connecting to MySQL databases is a very common requirement in Python development, especially when doing back-end development or data analysis. Python itself does not have the MySQL driver, but there are many third-party libraries that can help us implement this function.
Next, I will talk about how to connect to MySQL database in Python step by step.
Install the necessary libraries
Python To connect to MySQL, you need to first install a driver that supports MySQL. Commonly used are mysql-connector-python and pymysql . The usage of the two is similar. Here we take pymysql as an example.
You can use pip to install:
pip install pymysql
If you are using the Anaconda environment, you can also use conda to install:
conda install -c anaconda pymysql
After the installation is complete, you can start writing code.
Use PyMySQL to establish a connection
After installation, the next step is how to connect to the database using Python. The basic process is as follows:
- Import module
- Use
connect()method to establish a connection - Create a cursor object to execute SQL
- Get results or submit changes
- Close the connection
The sample code is as follows:
import pymysql
# Create a connection conn = pymysql.connect(
host='localhost',
user='your_username',
password='your_password',
database='your_database',
port=3306,
charset='utf8mb4'
)
# Create cursor cursor = conn.cursor()
# Execute the query statement cursor.execute("SELECT * FROM your_table")
# Get results = cursor.fetchall()
for row in results:
print(row)
# Close the connection cursor.close()
conn.close()Note: host does not necessarily mean localhost, it may also be the remote server IP; the default port is 3306, if it is not the default port, remember to change it.
Handle FAQs and Precautions
Not connecting to the database is one of the common problems encountered by novices. There are several possible reasons:
- Username and password error : The most common reason, especially remote databases, has stricter permission settings.
- The host name or IP is written incorrectly : Confirm whether the host is correct and whether remote access is allowed.
- Firewall restrictions : Some cloud servers (such as Alibaba Cloud and Tencent Cloud) do not open port 3306 by default, and security group rules need to be manually configured.
- Database service not running : If it is a local database, make sure that the MySQL service has been started.
- Character set problem : If you operate Chinese data, it is recommended to use utf8mb4 encoding, otherwise garbled code may occur.
If you are not sure where something went wrong, you can print exception information to help troubleshoot:
try:
conn = pymysql.connect(...)
except Exception as e:
print("Connection failed:", e)Optional: Automatically close the connection using the context manager
To prevent forgetting to close the connection, you can use the with context manager to automatically handle it:
with pymysql.connect(...) as conn:
with conn.cursor() as cursor:
cursor.execute("SELECT VERSION()")
print(cursor.fetchone()) This way, there is no need to call .close() manually, and Python will automatically help you with the resource release.
Basically that's it. Connecting to the database seems simple, but you may encounter various environmental configuration problems in the actual process. You can get familiar with it by trying a few more times.
The above is the detailed content of how to connect to mysql database from python. For more information, please follow other related articles on the PHP Chinese website!
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