A node.js driver for mysql. It is written in JavaScript, does not require compiling, and is 100% MIT licensed.
The mysql npm package is a Node.js client for interacting with MySQL databases. It allows users to connect to a MySQL database, execute queries, and handle database operations asynchronously.
Connecting to a MySQL database
This code establishes a connection to a MySQL database using the provided credentials.
const mysql = require('mysql');
const connection = mysql.createConnection({
host : 'localhost',
user : 'me',
password : 'secret',
database : 'my_db'
});
connection.connect();Executing a query
This code executes a SQL query to select all records from 'my_table' and logs the results.
connection.query('SELECT * FROM my_table', (error, results, fields) => {
if (error) throw error;
console.log(results);
});Inserting data
This code inserts a new record into the 'posts' table with the provided data object.
const post = {id: 1, title: 'Hello MySQL'};
const query = connection.query('INSERT INTO posts SET ?', post, (error, results, fields) => {
if (error) throw error;
// Neat!
});Updating data
This code updates the title of a record in the 'posts' table where the id is 5.
connection.query('UPDATE posts SET title = ? WHERE id = ?', ['Hello World', 5], (error, results, fields) => {
if (error) throw error;
// Updated successfully
});Closing the connection
This code closes the connection to the MySQL database.
connection.end();The pg package is a PostgreSQL client for Node.js. Similar to mysql, it allows for connecting to a PostgreSQL database, executing queries, and handling database operations. It is designed specifically for PostgreSQL, whereas mysql is for MySQL databases.
Sequelize is a promise-based Node.js ORM for Postgres, MySQL, MariaDB, SQLite, and Microsoft SQL Server. It provides a higher-level abstraction for database interactions and supports transactions, relations, eager and lazy loading, read replication, and more. It is more feature-rich and complex compared to the mysql package, which is a simple query client.
TypeORM is an ORM that can run in Node.js and be used with TypeScript or JavaScript (ES5, ES6, ES7, ES8). It supports MySQL, PostgreSQL, MariaDB, SQLite, MS SQL Server, Oracle, WebSQL databases. It provides a lot of advanced features like automatic migrations, data mapping, and a powerful query builder. It is more advanced and feature-rich compared to the mysql package.
Knex.js is a SQL query builder for Postgres, MSSQL, MySQL, MariaDB, SQLite3, Oracle, and Amazon Redshift, designed to be flexible, portable, and fun to use. It provides transaction support, connection pooling, and can be used as an SQL query builder in both Node.js and the browser. It is more versatile in terms of database support compared to the mysql package.
$ npm install mysql
For information about the previous 0.9.x releases, visit the v0.9 branch.
Sometimes I may also ask you to install the latest version from Github to check if a bugfix is working. In this case, please do:
$ npm install felixge/node-mysql
This is a node.js driver for mysql. It is written in JavaScript, does not require compiling, and is 100% MIT licensed.
Here is an example on how to use it:
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : 'me',
password : 'secret'
});
connection.connect();
connection.query('SELECT 1 + 1 AS solution', function(err, rows, fields) {
if (err) throw err;
console.log('The solution is: ', rows[0].solution);
});
connection.end();
From this example, you can learn the following:
end() which makes sure all remaining
queries are executed before sending a quit packet to the mysql server.Thanks goes to the people who have contributed code to this module, see the GitHub Contributors page.
Additionally I'd like to thank the following people:
The following companies have supported this project financially, allowing me to spend more time on it (ordered by time of contribution):
If you are interested in sponsoring a day or more of my time, please get in touch.
If you'd like to discuss this module, or ask questions about it, please use one of the following:
mysql)The recommended way to establish a connection is this:
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'example.org',
user : 'bob',
password : 'secret'
});
connection.connect(function(err) {
if (err) {
console.error('error connecting: ' + err.stack);
return;
}
console.log('connected as id ' + connection.threadId);
});
However, a connection can also be implicitly established by invoking a query:
var mysql = require('mysql');
var connection = mysql.createConnection(...);
connection.query('SELECT 1', function(err, rows) {
// connected! (unless `err` is set)
});
Depending on how you like to handle your errors, either method may be appropriate. Any type of connection error (handshake or network) is considered a fatal error, see the Error Handling section for more information.
When establishing a connection, you can set the following options:
host: The hostname of the database you are connecting to. (Default:
localhost)port: The port number to connect to. (Default: 3306)localAddress: The source IP address to use for TCP connection. (Optional)socketPath: The path to a unix domain socket to connect to. When used host
and port are ignored.user: The MySQL user to authenticate as.password: The password of that MySQL user.database: Name of the database to use for this connection (Optional).charset: The charset for the connection. This is called "collation" in the SQL-level
of MySQL (like utf8_general_ci). If a SQL-level charset is specified (like utf8mb4)
then the default collation for that charset is used. (Default: 'UTF8_GENERAL_CI')timezone: The timezone used to store local dates. (Default: 'local')connectTimeout: The milliseconds before a timeout occurs during the initial connection
to the MySQL server. (Default: 10000)stringifyObjects: Stringify objects instead of converting to values. See
issue #501. (Default: 'false')insecureAuth: Allow connecting to MySQL instances that ask for the old
(insecure) authentication method. (Default: false)typeCast: Determines if column values should be converted to native
JavaScript types. (Default: true)queryFormat: A custom query format function. See Custom format.supportBigNumbers: When dealing with big numbers (BIGINT and DECIMAL columns) in the database,
you should enable this option (Default: false).bigNumberStrings: Enabling both supportBigNumbers and bigNumberStrings forces big numbers
(BIGINT and DECIMAL columns) to be always returned as JavaScript String objects (Default: false).
Enabling supportBigNumbers but leaving bigNumberStrings disabled will return big numbers as String
objects only when they cannot be accurately represented with [JavaScript Number objects] (http://ecma262-5.com/ELS5_HTML.htm#Section_8.5)
(which happens when they exceed the [-2^53, +2^53] range), otherwise they will be returned as
Number objects. This option is ignored if supportBigNumbers is disabled.dateStrings: Force date types (TIMESTAMP, DATETIME, DATE) to be returned as strings rather then
inflated into JavaScript Date objects. (Default: false)debug: Prints protocol details to stdout. (Default: false)trace: Generates stack traces on Error to include call site of library
entrance ("long stack traces"). Slight performance penalty for most calls.
(Default: true)multipleStatements: Allow multiple mysql statements per query. Be careful
with this, it exposes you to SQL injection attacks. (Default: false)flags: List of connection flags to use other than the default ones. It is
also possible to blacklist default ones. For more information, check
Connection Flags.ssl: object with ssl parameters or a string containing name of ssl profile. See SSL options.In addition to passing these options as an object, you can also use a url string. For example:
var connection = mysql.createConnection('mysql://user:pass@host/db?debug=true&charset=BIG5_CHINESE_CI&timezone=-0700');
Note: The query values are first attempted to be parsed as JSON, and if that fails assumed to be plaintext strings.
The ssl option in the connection options takes a string or an object. When given a string,
it uses one of the predefined SSL profiles included. The following profiles are included:
"Amazon RDS": this profile is for connecting to an Amazon RDS server and contains the
certificates from https://rds.amazonaws.com/doc/rds-ssl-ca-cert.pem and
https://s3.amazonaws.com/rds-downloads/rds-combined-ca-bundle.pemWhen connecting to other servers, you will need to provide an object of options, in the same format as crypto.createCredentials. Please note the arguments expect a string of the certificate, not a file name to the certificate. Here is a simple example:
var connection = mysql.createConnection({
host : 'localhost',
ssl : {
ca : fs.readFileSync(__dirname + '/mysql-ca.crt')
}
});
You can also connect to a MySQL server without properly providing the appropriate CA to trust. You should not do this.
var connection = mysql.createConnection({
host : 'localhost',
ssl : {
// DO NOT DO THIS
// set up your ca correctly to trust the connection
rejectUnauthorized: false
}
});
There are two ways to end a connection. Terminating a connection gracefully is
done by calling the end() method:
connection.end(function(err) {
// The connection is terminated now
});
This will make sure all previously enqueued queries are still before sending a
COM_QUIT packet to the MySQL server. If a fatal error occurs before the
COM_QUIT packet can be sent, an err argument will be provided to the
callback, but the connection will be terminated regardless of that.
An alternative way to end the connection is to call the destroy() method.
This will cause an immediate termination of the underlying socket.
Additionally destroy() guarantees that no more events or callbacks will be
triggered for the connection.
connection.destroy();
Unlike end() the destroy() method does not take a callback argument.
Use pool directly.
var mysql = require('mysql');
var pool = mysql.createPool({
connectionLimit : 10,
host : 'example.org',
user : 'bob',
password : 'secret'
});
pool.query('SELECT 1 + 1 AS solution', function(err, rows, fields) {
if (err) throw err;
console.log('The solution is: ', rows[0].solution);
});
Connections can be pooled to ease sharing a single connection, or managing multiple connections.
var mysql = require('mysql');
var pool = mysql.createPool({
host : 'example.org',
user : 'bob',
password : 'secret'
});
pool.getConnection(function(err, connection) {
// connected! (unless `err` is set)
});
When you are done with a connection, just call connection.release() and the
connection will return to the pool, ready to be used again by someone else.
var mysql = require('mysql');
var pool = mysql.createPool(...);
pool.getConnection(function(err, connection) {
// Use the connection
connection.query( 'SELECT something FROM sometable', function(err, rows) {
// And done with the connection.
connection.release();
// Don't use the connection here, it has been returned to the pool.
});
});
If you would like to close the connection and remove it from the pool, use
connection.destroy() instead. The pool will create a new connection the next
time one is needed.
Connections are lazily created by the pool. If you configure the pool to allow up to 100 connections, but only ever use 5 simultaneously, only 5 connections will be made. Connections are also cycled round-robin style, with connections being taken from the top of the pool and returning to the bottom.
When a previous connection is retrieved from the pool, a ping packet is sent to the server to check if the connection is still good.
Pools accept all the same options as a connection. When creating a new connection, the options are simply passed to the connection constructor. In addition to those options pools accept a few extras:
acquireTimeout: The milliseconds before a timeout occurs during the connection
acquisition. This is slightly different from connectTimeout, because acquiring
a pool connection does not always involve making a connection. (Default: 10000)waitForConnections: Determines the pool's action when no connections are
available and the limit has been reached. If true, the pool will queue the
connection request and call it when one becomes available. If false, the
pool will immediately call back with an error. (Default: true)connectionLimit: The maximum number of connections to create at once.
(Default: 10)queueLimit: The maximum number of connection requests the pool will queue
before returning an error from getConnection. If set to 0, there is no
limit to the number of queued connection requests. (Default: 0)The pool will emit a connection event when a new connection is made within the pool.
If you need to set session variables on the connection before it gets used, you can
listen to the connection event.
pool.on('connection', function (connection) {
connection.query('SET SESSION auto_increment_increment=1')
});
The pool will emit an enqueue event when a callback has been queued to wait for
an available connection.
pool.on('enqueue', function () {
console.log('Waiting for available connection slot');
});
When you are done using the pool, you have to end all the connections or the
Node.js event loop will stay active until the connections are closed by the
MySQL server. This is typically done if the pool is used in a script or when
trying to gracefully shutdown a server. To end all the connections in the
pool, use the end method on the pool:
pool.end(function (err) {
// all connections in the pool have ended
});
The end method takes an optional callback that you can use to know once
all the connections have ended. The connections end gracefully, so all
pending queries will still complete and the time to end the pool will vary.
Once pool.end() has been called, pool.getConnection and other operations
can no longer be performed
PoolCluster provides multiple hosts connection. (group & retry & selector)
// create
var poolCluster = mysql.createPoolCluster();
poolCluster.add(config); // anonymous group
poolCluster.add('MASTER', masterConfig);
poolCluster.add('SLAVE1', slave1Config);
poolCluster.add('SLAVE2', slave2Config);
// Target Group : ALL(anonymous, MASTER, SLAVE1-2), Selector : round-robin(default)
poolCluster.getConnection(function (err, connection) {});
// Target Group : MASTER, Selector : round-robin
poolCluster.getConnection('MASTER', function (err, connection) {});
// Target Group : SLAVE1-2, Selector : order
// If can't connect to SLAVE1, return SLAVE2. (remove SLAVE1 in the cluster)
poolCluster.on('remove', function (nodeId) {
console.log('REMOVED NODE : ' + nodeId); // nodeId = SLAVE1
});
poolCluster.getConnection('SLAVE*', 'ORDER', function (err, connection) {});
// of namespace : of(pattern, selector)
poolCluster.of('*').getConnection(function (err, connection) {});
var pool = poolCluster.of('SLAVE*', 'RANDOM');
pool.getConnection(function (err, connection) {});
pool.getConnection(function (err, connection) {});
// destroy
poolCluster.end();
canRetry: If true, PoolCluster will attempt to reconnect when connection fails. (Default: true)removeNodeErrorCount: If connection fails, node's errorCount increases.
When errorCount is greater than removeNodeErrorCount, remove a node in the PoolCluster. (Default: 5)defaultSelector: The default selector. (Default: RR)
RR: Select one alternately. (Round-Robin)RANDOM: Select the node by random function.ORDER: Select the first node available unconditionally.var clusterConfig = {
removeNodeErrorCount: 1, // Remove the node immediately when connection fails.
defaultSelector: 'ORDER'
};
var poolCluster = mysql.createPoolCluster(clusterConfig);
MySQL offers a changeUser command that allows you to alter the current user and other aspects of the connection without shutting down the underlying socket:
connection.changeUser({user : 'john'}, function(err) {
if (err) throw err;
});
The available options for this feature are:
user: The name of the new user (defaults to the previous one).password: The password of the new user (defaults to the previous one).charset: The new charset (defaults to the previous one).database: The new database (defaults to the previous one).A sometimes useful side effect of this functionality is that this function also resets any connection state (variables, transactions, etc.).
Errors encountered during this operation are treated as fatal connection errors by this module.
You may lose the connection to a MySQL server due to network problems, the
server timing you out, the server being restarted, or crashing. All of these
events are considered fatal errors, and will have the err.code = 'PROTOCOL_CONNECTION_LOST'. See the Error Handling section
for more information.
Re-connecting a connection is done by establishing a new connection. Once terminated, an existing connection object cannot be re-connected by design.
With Pool, disconnected connections will be removed from the pool freeing up space for a new connection to be created on the next getConnection call.
In order to avoid SQL Injection attacks, you should always escape any user
provided data before using it inside a SQL query. You can do so using the
mysql.escape(), connection.escape() or pool.escape() methods:
var userId = 'some user provided value';
var sql = 'SELECT * FROM users WHERE id = ' + connection.escape(userId);
connection.query(sql, function(err, results) {
// ...
});
Alternatively, you can use ? characters as placeholders for values you would
like to have escaped like this:
connection.query('SELECT * FROM users WHERE id = ?', [userId], function(err, results) {
// ...
});
This looks similar to prepared statements in MySQL, however it really just uses
the same connection.escape() method internally.
Caution This also differs from prepared statements in that all ? are
replaced, even those contained in comments and strings.
Different value types are escaped differently, here is how:
true / false strings'YYYY-mm-dd HH:ii:ss' stringsX'0fa5'['a', 'b'] turns into 'a', 'b'[['a', 'b'], ['c', 'd']] turns into ('a', 'b'), ('c', 'd')key = 'val' pairs for each enumerable property on
the object. If the property's value is a function, it is skipped; if the
property's value is an object, toString() is called on it and the returned
value is used.undefined / null are converted to NULLNaN / Infinity are left as-is. MySQL does not support these, and trying
to insert them as values will trigger MySQL errors until they implement
support.If you paid attention, you may have noticed that this escaping allows you to do neat things like this:
var post = {id: 1, title: 'Hello MySQL'};
var query = connection.query('INSERT INTO posts SET ?', post, function(err, result) {
// Neat!
});
console.log(query.sql); // INSERT INTO posts SET `id` = 1, `title` = 'Hello MySQL'
If you feel the need to escape queries by yourself, you can also use the escaping function directly:
var query = "SELECT * FROM posts WHERE title=" + mysql.escape("Hello MySQL");
console.log(query); // SELECT * FROM posts WHERE title='Hello MySQL'
If you can't trust an SQL identifier (database / table / column name) because it is
provided by a user, you should escape it with mysql.escapeId(identifier),
connection.escapeId(identifier) or pool.escapeId(identifier) like this:
var sorter = 'date';
var sql = 'SELECT * FROM posts ORDER BY ' + connection.escapeId(sorter);
connection.query(sql, function(err, results) {
// ...
});
It also supports adding qualified identifiers. It will escape both parts.
var sorter = 'date';
var sql = 'SELECT * FROM posts ORDER BY ' + connection.escapeId('posts.' + sorter);
connection.query(sql, function(err, results) {
// ...
});
Alternatively, you can use ?? characters as placeholders for identifiers you would
like to have escaped like this:
var userId = 1;
var columns = ['username', 'email'];
var query = connection.query('SELECT ?? FROM ?? WHERE id = ?', [columns, 'users', userId], function(err, results) {
// ...
});
console.log(query.sql); // SELECT `username`, `email` FROM `users` WHERE id = 1
Please note that this last character sequence is experimental and syntax might change
When you pass an Object to .escape() or .query(), .escapeId() is used to avoid SQL injection in object keys.
You can use mysql.format to prepare a query with multiple insertion points, utilizing the proper escaping for ids and values. A simple example of this follows:
var sql = "SELECT * FROM ?? WHERE ?? = ?";
var inserts = ['users', 'id', userId];
sql = mysql.format(sql, inserts);
Following this you then have a valid, escaped query that you can then send to the database safely. This is useful if you are looking to prepare the query before actually sending it to the database. As mysql.format is exposed from SqlString.format you also have the option (but are not required) to pass in stringifyObject and timezone, allowing you provide a custom means of turning objects into strings, as well as a location-specific/timezone-aware Date.
If you prefer to have another type of query escape format, there's a connection configuration option you can use to define a custom format function. You can access the connection object if you want to use the built-in .escape() or any other connection function.
Here's an example of how to implement another format:
connection.config.queryFormat = function (query, values) {
if (!values) return query;
return query.replace(/\:(\w+)/g, function (txt, key) {
if (values.hasOwnProperty(key)) {
return this.escape(values[key]);
}
return txt;
}.bind(this));
};
connection.query("UPDATE posts SET title = :title", { title: "Hello MySQL" });
If you are inserting a row into a table with an auto increment primary key, you can retrieve the insert id like this:
connection.query('INSERT INTO posts SET ?', {title: 'test'}, function(err, result) {
if (err) throw err;
console.log(result.insertId);
});
When dealing with big numbers (above JavaScript Number precision limit), you should
consider enabling supportBigNumbers option to be able to read the insert id as a
string, otherwise it will throw.
This option is also required when fetching big numbers from the database, otherwise you will get values rounded to hundreds or thousands due to the precision limit.
You can get the number of affected rows from an insert, update or delete statement.
connection.query('DELETE FROM posts WHERE title = "wrong"', function (err, result) {
if (err) throw err;
console.log('deleted ' + result.affectedRows + ' rows');
})
You can get the number of changed rows from an update statement.
"changedRows" differs from "affectedRows" in that it does not count updated rows whose values were not changed.
connection.query('UPDATE posts SET ...', function (err, result) {
if (err) throw err;
console.log('changed ' + result.changedRows + ' rows');
})
You can get the MySQL connection ID ("thread ID") of a given connection using the threadId
property.
connection.connect(function(err) {
if (err) throw err;
console.log('connected as id ' + connection.threadId);
});
The MySQL protocol is sequential, this means that you need multiple connections to execute queries in parallel. You can use a Pool to manage connections, one simple approach is to create one connection per incoming http request.
Sometimes you may want to select large quantities of rows and process each of them as they are received. This can be done like this:
var query = connection.query('SELECT * FROM posts');
query
.on('error', function(err) {
// Handle error, an 'end' event will be emitted after this as well
})
.on('fields', function(fields) {
// the field packets for the rows to follow
})
.on('result', function(row) {
// Pausing the connnection is useful if your processing involves I/O
connection.pause();
processRow(row, function() {
connection.resume();
});
})
.on('end', function() {
// all rows have been received
});
Please note a few things about the example above:
pause(). This number will depend on the
amount and size of your rows.pause() / resume() operate on the underlying socket and parser. You are
guaranteed that no more 'result' events will fire after calling pause().query() method when streaming rows.'result' event will fire for both rows as well as OK packets
confirming the success of a INSERT/UPDATE query.Additionally you may be interested to know that it is currently not possible to stream individual row columns, they will always be buffered up entirely. If you have a good use case for streaming large fields to and from MySQL, I'd love to get your thoughts and contributions on this.
The query object provides a convenience method .stream([options]) that wraps
query events into a Readable
Streams2Streams2 object. This
stream can easily be piped downstream and provides automatic pause/resume,
based on downstream congestion and the optional highWaterMark. The
objectMode parameter of the stream is set to true and cannot be changed
(if you need a byte stream, you will need to use a transform stream, like
objstream for example).
For example, piping query results into another stream (with a max buffer of 5 objects) is simply:
connection.query('SELECT * FROM posts')
.stream({highWaterMark: 5})
.pipe(...);
Support for multiple statements is disabled for security reasons (it allows for SQL injection attacks if values are not properly escaped). To use this feature you have to enable it for your connection:
var connection = mysql.createConnection({multipleStatements: true});
Once enabled, you can execute multiple statement queries like any other query:
connection.query('SELECT 1; SELECT 2', function(err, results) {
if (err) throw err;
// `results` is an array with one element for every statement in the query:
console.log(results[0]); // [{1: 1}]
console.log(results[1]); // [{2: 2}]
});
Additionally you can also stream the results of multiple statement queries:
var query = connection.query('SELECT 1; SELECT 2');
query
.on('fields', function(fields, index) {
// the fields for the result rows that follow
})
.on('result', function(row, index) {
// index refers to the statement this result belongs to (starts at 0)
});
If one of the statements in your query causes an error, the resulting Error
object contains a err.index property which tells you which statement caused
it. MySQL will also stop executing any remaining statements when an error
occurs.
Please note that the interface for streaming multiple statement queries is experimental and I am looking forward to feedback on it.
You can call stored procedures from your queries as with any other mysql driver. If the stored procedure produces several result sets, they are exposed to you the same way as the results for multiple statement queries.
When executing joins, you are likely to get result sets with overlapping column names.
By default, node-mysql will overwrite colliding column names in the order the columns are received from MySQL, causing some of the received values to be unavailable.
However, you can also specify that you want your columns to be nested below the table name like this:
var options = {sql: '...', nestTables: true};
connection.query(options, function(err, results) {
/* results will be an array like this now:
[{
table1: {
fieldA: '...',
fieldB: '...',
},
table2: {
fieldA: '...',
fieldB: '...',
},
}, ...]
*/
});
Or use a string separator to have your results merged.
var options = {sql: '...', nestTables: '_'};
connection.query(options, function(err, results) {
/* results will be an array like this now:
[{
table1_fieldA: '...',
table1_fieldB: '...',
table2_fieldA: '...',
table2_fieldB: '...',
}, ...]
*/
});
Simple transaction support is available at the connection level:
connection.beginTransaction(function(err) {
if (err) { throw err; }
connection.query('INSERT INTO posts SET title=?', title, function(err, result) {
if (err) {
connection.rollback(function() {
throw err;
});
}
var log = 'Post ' + result.insertId + ' added';
connection.query('INSERT INTO log SET data=?', log, function(err, result) {
if (err) {
connection.rollback(function() {
throw err;
});
}
connection.commit(function(err) {
if (err) {
connection.rollback(function() {
throw err;
});
}
console.log('success!');
});
});
});
});
Please note that beginTransaction(), commit() and rollback() are simply convenience functions that execute the START TRANSACTION, COMMIT, and ROLLBACK commands respectively. It is important to understand that many commands in MySQL can cause an implicit commit, as described in the MySQL documentation
A ping packet can be sent over a connection using the connection.ping method. This
mehtod will send a ping packet to the server and when the server responds, the callback
will fire. If an error occurred, the callback will fire with an error argument.
connection.ping(function (err) {
if (err) throw err;
console.log('Server responded to ping');
})
Every operation takes an optional inactivity timeout option. This allows you to specify appropriate timeouts for operations. It is important to note that these timeouts are not part of the MySQL protocol, and rather timeout operations through the client. This means that when a timeout is reached, the connection it occurred on will be destroyed and no further operations can be performed.
// Kill query after 60s
connection.query({sql: 'SELECT COUNT(*) AS count FROM big_table', timeout: 60000}, function (err, rows) {
if (err && err.code === 'PROTOCOL_SEQUENCE_TIMEOUT') {
throw new Error('too long to count table rows!');
}
if (err) {
throw err;
}
console.log(rows[0].count + ' rows');
});
This module comes with a consistent approach to error handling that you should review carefully in order to write solid applications.
All errors created by this module are instances of the JavaScript Error object. Additionally they come with two properties:
err.code: Either a MySQL server error (e.g.
'ER_ACCESS_DENIED_ERROR'), a node.js error (e.g. 'ECONNREFUSED') or an
internal error (e.g. 'PROTOCOL_CONNECTION_LOST').err.fatal: Boolean, indicating if this error is terminal to the connection
object.Fatal errors are propagated to all pending callbacks. In the example below, a fatal error is triggered by trying to connect to an invalid port. Therefore the error object is propagated to both pending callbacks:
var connection = require('mysql').createConnection({
port: 84943, // WRONG PORT
});
connection.connect(function(err) {
console.log(err.code); // 'ECONNREFUSED'
console.log(err.fatal); // true
});
connection.query('SELECT 1', function(err) {
console.log(err.code); // 'ECONNREFUSED'
console.log(err.fatal); // true
});
Normal errors however are only delegated to the callback they belong to. So in the example below, only the first callback receives an error, the second query works as expected:
connection.query('USE name_of_db_that_does_not_exist', function(err, rows) {
console.log(err.code); // 'ER_BAD_DB_ERROR'
});
connection.query('SELECT 1', function(err, rows) {
console.log(err); // null
console.log(rows.length); // 1
});
Last but not least: If a fatal errors occurs and there are no pending
callbacks, or a normal error occurs which has no callback belonging to it, the
error is emitted as an 'error' event on the connection object. This is
demonstrated in the example below:
connection.on('error', function(err) {
console.log(err.code); // 'ER_BAD_DB_ERROR'
});
connection.query('USE name_of_db_that_does_not_exist');
Note: 'error' are special in node. If they occur without an attached
listener, a stack trace is printed and your process is killed.
tl;dr: This module does not want you to deal with silent failures. You should always provide callbacks to your method calls. If you want to ignore this advice and suppress unhandled errors, you can do this:
// I am Chuck Norris:
connection.on('error', function() {});
This module is exception safe. That means you can continue to use it, even if one of your callback functions throws an error which you're catching using 'uncaughtException' or a domain.
For your convenience, this driver will cast mysql types into native JavaScript types by default. The following mappings exist:
It is not recommended (and may go away / change in the future) to disable type casting, but you can currently do so on either the connection:
var connection = require('mysql').createConnection({typeCast: false});
Or on the query level:
var options = {sql: '...', typeCast: false};
var query = connection.query(options, function(err, results) {
});
You can also pass a function and handle type casting yourself. You're given some
column information like database, table and name and also type and length. If you
just want to apply a custom type casting to a specific type you can do it and then
fallback to the default. Here's an example of converting TINYINT(1) to boolean:
connection.query({
sql: '...',
typeCast: function (field, next) {
if (field.type == 'TINY' && field.length == 1) {
return (field.string() == '1'); // 1 = true, 0 = false
}
return next();
}
});
WARNING: YOU MUST INVOKE the parser using one of these three field functions in your custom typeCast callback. They can only be called once.( see #539 for discussion)
field.string()
field.buffer()
field.geometry()
are aliases for
parser.parseLengthCodedString()
parser.parseLengthCodedBuffer()
parser.parseGeometryValue()
You can find which field function you need to use by looking at: RowDataPacket.prototype._typeCast
If, for any reason, you would like to change the default connection flags, you
can use the connection option flags. Pass a string with a comma separated list
of items to add to the default flags. If you don't want a default flag to be used
prepend the flag with a minus sign. To add a flag that is not in the default list,
just write the flag name, or prefix it with a plus (case insensitive).
Please note that some available flags that are not not supported (e.g.: Compression), are still not allowed to be specified.
The next example blacklists FOUND_ROWS flag from default connection flags.
var connection = mysql.createConnection("mysql://localhost/test?flags=-FOUND_ROWS");
The following flags are sent by default on a new connection:
CONNECT_WITH_DB - Ability to specify the database on connection.FOUND_ROWS - Send the found rows instead of the affected rows as affectedRows.IGNORE_SIGPIPE - Old; no effect.IGNORE_SPACE - Let the parser ignore spaces before the ( in queries.LOCAL_FILES - Can use LOAD DATA LOCAL.LONG_FLAGLONG_PASSWORD - Use the improved version of Old Password Authentication.MULTI_RESULTS - Can handle multiple resultsets for COM_QUERY.ODBC Old; no effect.PROTOCOL_41 - Uses the 4.1 protocol.PS_MULTI_RESULTS - Can handle multiple resultsets for COM_STMT_EXECUTE.RESERVED - Old flag for the 4.1 protocol.SECURE_CONNECTION - Support native 4.1 authentication.TRANSACTIONS - Asks for the transaction status flags.In addition, the following flag will be sent if the option multipleStatements
is set to true:
MULTI_STATEMENTS - The client may send multiple statement per query or
statement prepare.There are other flags available. They may or may not function, but are still available to specify.
If you are running into problems, one thing that may help is enabling the
debug mode for the connection:
var connection = mysql.createConnection({debug: true});
This will print all incoming and outgoing packets on stdout. You can also restrict debugging to packet types by passing an array of types to debug:
var connection = mysql.createConnection({debug: ['ComQueryPacket', 'RowDataPacket']});
to restrict debugging to the query and data packets.
If that does not help, feel free to open a GitHub issue. A good GitHub issue will have:
The test suite is split into two parts: unit tests and integration tests. The unit tests run on any machine while the integration tests require a MySQL server instance to be setup.
$ FILTER=unit npm test
Set the environment variables MYSQL_DATABASE, MYSQL_HOST, MYSQL_PORT,
MYSQL_USER and MYSQL_PASSWORD. Then run npm test.
For example, if you have an installation of mysql running on localhost:3306
and no password set for the root user, run:
$ mysql -u root -e "CREATE DATABASE IF NOT EXISTS node_mysql_test"
$ MYSQL_HOST=localhost MYSQL_PORT=3306 MYSQL_DATABASE=node_mysql_test MYSQL_USER=root MYSQL_PASSWORD= FILTER=integration npm test
FAQs
A node.js driver for mysql. It is written in JavaScript, does not require compiling, and is 100% MIT licensed.
The npm package mysql receives a total of 377,910 weekly downloads. As such, mysql popularity was classified as popular.
We found that mysql demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 4 open source maintainers collaborating on the project.
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