To connect MySQL data to Node.js application, 1. Install the mysql2 module; 2. Create a connection configuration, including host, user, password, database, etc.; 3. Establish a connection and handle errors; 4. Execute SQL queries and process results; 5. Close the connection or use the connection pool to manage the connection; Common problems include network blockage, insufficient account permissions, firewall restrictions, password errors and SSL connection problems. Follow the steps to troubleshoot.
Connecting MySQL database to Node.js application is not complicated, but some details are prone to errors. As long as you are prepared for dependencies and configured correctly, you can basically connect smoothly.
The following is a few common steps and points to pay attention to how to do it.
Install the MySQL module
Node.js itself does not have built-in MySQL support, you need to install a MySQL client module first. The most commonly used is mysql or mysql2 , which has better performance and also supports Promise.
Run command to install:
npm install mysql2
If you don't want to change modules, it's OK to continue using mysql , but it is recommended to use mysql2 , which has good compatibility.
Create a connection configuration
Before connecting to the database, you need to prepare the connection information. Including host name, user name, password, database name, and optional port.
Usually you will write a configuration object, such as this:
const mysql = require('mysql2');
const connection = mysql.createConnection({
host: 'localhost',
user: 'your_username',
password: 'your_password',
database: 'your_database'
});These parameters must be filled in according to your actual database environment. For example, if the database is not local, the host must be changed to the corresponding IP or domain name.
Establish a connection and execute a query
After creating the configuration, you can establish a connection:
connection.connect((err) => {
if (err) {
console.error('Connection failed:', err.stack);
return;
}
console.log('Connection is successful, ID is:', connection.threadId);
});After the connection is successful, you can execute SQL query:
connection.query('SELECT 1 1 AS solution', (error, results, fields) => {
if (error) throw error;
console.log('Query result:', results[0].solution);
});Don't forget to close the connection at the end:
connection.end();
Or if you want to control the connection life cycle more flexibly, you can use a connection pool, which is suitable for applications with many concurrent requests.
Frequently Asked Questions
- Network blockage : The remote database needs to confirm whether the current IP connection is allowed.
- Insufficient account permissions : Whether MySQL users have permission to access the corresponding database.
- Firewall restrictions : Port 3306 may be open on cloud servers.
- Password error or user does not exist : Check whether the username and password are accurate.
- SSL connection issues : Some managed databases require SSL to be mandated, and you can add
ssl: 'Amazon RDS'or other modes to the configuration.
If you report an error ER_ACCESS_DENIED_ERROR when connecting, it is likely that the user name or password is wrong; if it is ECONNREFUSED , it may be that the database is not running or the port is not running.
Basically that's it. Follow these steps to connect to MySQL in most cases.
The above is the detailed content of how to connect to mysql from node.js. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undress AI Tool
Undress images for free
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
Analyzing the MySQL Slow Query Log to Find Performance Bottlenecks
Jul 04, 2025 am 02:46 AM
Turn on MySQL slow query logs and analyze locationable performance issues. 1. Edit the configuration file or dynamically set slow_query_log and long_query_time; 2. The log contains key fields such as Query_time, Lock_time, Rows_examined to assist in judging efficiency bottlenecks; 3. Use mysqldumpslow or pt-query-digest tools to efficiently analyze logs; 4. Optimization suggestions include adding indexes, avoiding SELECT*, splitting complex queries, etc. For example, adding an index to user_id can significantly reduce the number of scanned rows and improve query efficiency.
Performing logical backups using mysqldump in MySQL
Jul 06, 2025 am 02:55 AM
mysqldump is a common tool for performing logical backups of MySQL databases. It generates SQL files containing CREATE and INSERT statements to rebuild the database. 1. It does not back up the original file, but converts the database structure and content into portable SQL commands; 2. It is suitable for small databases or selective recovery, and is not suitable for fast recovery of TB-level data; 3. Common options include --single-transaction, --databases, --all-databases, --routines, etc.; 4. Use mysql command to import during recovery, and can turn off foreign key checks to improve speed; 5. It is recommended to test backup regularly, use compression, and automatic adjustment.
Handling NULL Values in MySQL Columns and Queries
Jul 05, 2025 am 02:46 AM
When handling NULL values ??in MySQL, please note: 1. When designing the table, the key fields are set to NOTNULL, and optional fields are allowed NULL; 2. ISNULL or ISNOTNULL must be used with = or !=; 3. IFNULL or COALESCE functions can be used to replace the display default values; 4. Be cautious when using NULL values ??directly when inserting or updating, and pay attention to the data source and ORM framework processing methods. NULL represents an unknown value and does not equal any value, including itself. Therefore, be careful when querying, counting, and connecting tables to avoid missing data or logical errors. Rational use of functions and constraints can effectively reduce interference caused by NULL.
Managing Transactions and Locking Behavior in MySQL
Jul 04, 2025 am 02:24 AM
MySQL transactions and lock mechanisms are key to concurrent control and performance tuning. 1. When using transactions, be sure to explicitly turn on and keep the transactions short to avoid resource occupation and undolog bloating due to long transactions; 2. Locking operations include shared locks and exclusive locks, SELECT...FORUPDATE plus X locks, SELECT...LOCKINSHAREMODE plus S locks, write operations automatically locks, and indexes should be used to reduce the lock granularity; 3. The isolation level is repetitively readable by default, suitable for most scenarios, and modifications should be cautious; 4. Deadlock inspection can analyze the details of the latest deadlock through the SHOWENGINEINNODBSTATUS command, and the optimization methods include unified execution order, increase indexes, and introduce queue systems.
Aggregating data with GROUP BY and HAVING clauses in MySQL
Jul 05, 2025 am 02:42 AM
GROUPBY is used to group data by field and perform aggregation operations, and HAVING is used to filter the results after grouping. For example, using GROUPBYcustomer_id can calculate the total consumption amount of each customer; using HAVING can filter out customers with a total consumption of more than 1,000. The non-aggregated fields after SELECT must appear in GROUPBY, and HAVING can be conditionally filtered using an alias or original expressions. Common techniques include counting the number of each group, grouping multiple fields, and filtering with multiple conditions.
Paginating Results with LIMIT and OFFSET in MySQL
Jul 05, 2025 am 02:41 AM
MySQL paging is commonly implemented using LIMIT and OFFSET, but its performance is poor under large data volume. 1. LIMIT controls the number of each page, OFFSET controls the starting position, and the syntax is LIMITNOFFSETM; 2. Performance problems are caused by excessive records and discarding OFFSET scans, resulting in low efficiency; 3. Optimization suggestions include using cursor paging, index acceleration, and lazy loading; 4. Cursor paging locates the starting point of the next page through the unique value of the last record of the previous page, avoiding OFFSET, which is suitable for "next page" operation, and is not suitable for random jumps.
Setting up asynchronous primary-replica replication in MySQL
Jul 06, 2025 am 02:52 AM
To set up asynchronous master-slave replication for MySQL, follow these steps: 1. Prepare the master server, enable binary logs and set a unique server-id, create a replication user and record the current log location; 2. Use mysqldump to back up the master library data and import it to the slave server; 3. Configure the server-id and relay-log of the slave server, use the CHANGEMASTER command to connect to the master library and start the replication thread; 4. Check for common problems, such as network, permissions, data consistency and self-increase conflicts, and monitor replication delays. Follow the steps above to ensure that the configuration is completed correctly.
Calculating Database and Table Sizes in MySQL
Jul 06, 2025 am 02:41 AM
To view the size of the MySQL database and table, you can query the information_schema directly or use the command line tool. 1. Check the entire database size: Execute the SQL statement SELECTtable_schemaAS'Database',SUM(data_length index_length)/1024/1024AS'Size(MB)'FROMinformation_schema.tablesGROUPBYtable_schema; you can get the total size of all databases, or add WHERE conditions to limit the specific database; 2. Check the single table size: use SELECTta
