类似于执行单个语句，提交或回滚事务也会触发警告。为了能够处理这些警告，需要检查 Session.commit(); 或 Session.rollback(); 的回复结果对象。

以下示例演示了这一点。示例假设测试模式已存在并且集合 my_collection 不存在。

MySQL Shell JavaScript 代码

var mysqlx = require('mysqlx');

// Connect to server
var mySession = mysqlx.getSession( {
        host: 'localhost', port: 33060,
        user: 'user', password: 'password' } );

// Get the Schema test
var myDb = mySession.getSchema('test');

// Create a new collection
var myColl = myDb.createCollection('my_collection');

// Start a transaction
mySession.startTransaction();
try
{
    myColl.add({'name': 'Rohit', 'age': 18, 'height': 1.76}).execute();
    myColl.add({'name': 'Misaki', 'age': 24, 'height': 1.65}).execute();
    myColl.add({'name': 'Leon', 'age': 39, 'height': 1.9}).execute();

    // Commit the transaction if everything went well
    var reply = mySession.commit();

    // handle warnings
    if (reply.warningCount){
      var warnings = reply.getWarnings();
      for (index in warnings){
        var warning = warnings[index];
        print ('Type ['+ warning.level + '] (Code ' + warning.code + '): ' + warning.message + '\n');
      }
    }

    print ('Data inserted successfully.');
}
catch(err)
{
    // Rollback the transaction in case of an error
    reply = mySession.rollback();

    // handle warnings
    if (reply.warningCount){
      var warnings = reply.getWarnings();
      for (index in warnings){
        var warning = warnings[index];
        print ('Type ['+ warning.level + '] (Code ' + warning.code + '): ' + warning.message + '\n');
      }
    }

    // Printing the error message
    print ('Data could not be inserted: ' + err.message);
}

MySQL Shell Python 代码

from mysqlsh import mysqlx

# Connect to server
mySession = mysqlx.get_session( {
        'host': 'localhost', 'port': 33060,
        'user': 'user', 'password': 'password' } )

# Get the Schema test
myDb = mySession.get_schema('test')

# Create a new collection
myColl = myDb.create_collection('my_collection')

# Start a transaction
mySession.start_transaction()
try:
    myColl.add({'name': 'Rohit', 'age': 18, 'height': 1.76}).execute()
    myColl.add({'name': 'Misaki', 'age': 24, 'height': 1.65}).execute()
    myColl.add({'name': 'Leon', 'age': 39, 'height': 1.9}).execute()

    # Commit the transaction if everything went well
    reply = mySession.commit()

    # handle warnings
    if reply.warning_count:
      for warning in result.get_warnings():
        print('Type [%s] (Code %s): %s\n' % (warning.level, warning.code, warning.message))

    print('Data inserted successfully.')
except Exception as err:
    # Rollback the transaction in case of an error
    reply = mySession.rollback()

    # handle warnings
    if reply.warning_count:
      for warning in result.get_warnings():
        print('Type [%s] (Code %s): %s\n' % (warning.level, warning.code, warning.message))

    # Printing the error message
    print('Data could not be inserted: %s' % str(err))

C# 代码

// Connect to server
var session = MySQLX.GetSession("server=localhost;port=33060;user=user;password=password;");

// Get the Schema test
var db = session.GetSchema("test");

// Create a new collection
var myColl = db.CreateCollection("my_collection");

// Start a transaction
session.StartTransaction();
int warningCount = 0;
try
{
	var result = myColl.Add(new { name = "Rohit", age = 18, height = 1.76}).Execute();
	warningCount += result.Warnings.Count;
	result = myColl.Add(new { name = "Misaki", age = 24, height = 1.65}).Execute();
	warningCount += result.Warnings.Count;
	result = myColl.Add(new { name = "Leon", age = 39, height = 1.9}).Execute();
	warningCount += result.Warnings.Count;

	// Commit the transaction if everything went well
	session.Commit();
	if(warningCount > 0)
	{
	  // handle warnings
	}

	Console.WriteLine("Data inserted successfully.");
}
catch (Exception err)
{
	// Rollback the transaction in case of an error
	session.Rollback();
	if(warningCount > 0)
	{
	  // handle warnings
	}

	// Printing the error message
	Console.WriteLine("Data could not be inserted: " + err.Message);
}

Python 代码

import mysqlx

# Connect to server
my_session = mysqlx.get_session({
    'host': 'localhost', 'port': 33060,
    'user': 'user', 'password': 'password'
})

# Get the Schema test
my_schema = my_session.get_schema('test')

# Create a new collection
my_coll = my_schema.create_collection('my_collection')

# Start a transaction
my_session.start_transaction()
try:
    my_coll.add({'name': 'Rohit', 'age': 18, 'height': 1.76}).execute()
    my_coll.add({'name': 'Misaki', 'age': 24, 'height': 1.65}).execute()
    my_coll.add({'name': 'Leon', 'age': 39, 'height': 1.9}).execute()

    # Commit the transaction if everything went well
    result = my_session.commit()

    # handle warnings
    if result.get_warnings_count() > 0:
        for warning in result.get_warnings():
            print('Type [{0}] (Code {1}): {2}'.format(warning['level'], warning['code'], warning['msg']))

    print('Data inserted successfully.')
except Exception as err:
    # Rollback the transaction in case of an error
    result = my_session.rollback()

    # handle warnings
    if result.get_warnings_count() > 0:
        for warning in result.get_warnings():
            print('Type [{0}] (Code {1}): {2}'.format(warning['level'], warning['code'], warning['msg']))

    # Printing the error message
    print('Data could not be inserted: {0}'.format(err))

Java 代码

// c.f. "standard transaction handling"

C++ 代码

/*
  Connector/C++ does not yet provide access to transaction warnings
  -- Session methods commit() and rollback() do not return a result object.
*/

默认情况下，所有警告都从服务器发送到客户端。如果已知某个操作会生成许多警告，并且这些警告对应用程序没有价值，则可以抑制发送警告。这有助于节省带宽。session.setFetchWarnings() 控制是在服务器上丢弃警告还是将其发送到客户端。session.getFetchWarnings() 用于了解当前活动的设置。

MySQL Shell JavaScript 代码

var mysqlx = require('mysqlx');

function process_warnings(result){
  if (result.getWarningCount()){
    var warnings = result.getWarnings();
    for (index in warnings){
      var warning = warnings[index];
      print ('Type ['+ warning.level + '] (Code ' + warning.code + '): ' + warning.message + '\n');
    }
  }
  else{
    print ("No warnings were returned.\n");
  }
}

// Connect to server
var mySession = mysqlx.getSession( {
  host: 'localhost', port: 33060,
  user: 'user', password: 'password' } );

// Disables warning generation
mySession.setFetchWarnings(false);
var result = mySession.sql('drop schema if exists unexisting').execute();
process_warnings(result);

// Enables warning generation
mySession.setFetchWarnings(true);
var result = mySession.sql('drop schema if exists unexisting').execute();
process_warnings(result);

MySQL Shell Python 代码

from mysqlsh import mysqlx

def process_warnings(result):
  if result.get_warnings_count():
    for warning in result.get_warnings():
      print('Type [%s] (Code %s): %s\n' % (warning.level, warning.code, warning.message))
  else:
    print("No warnings were returned.\n")


# Connect to server
mySession = mysqlx.get_session( {
  'host': 'localhost', 'port': 33060,
  'user': 'user', 'password': 'password' } );

# Disables warning generation
mySession.set_fetch_warnings(False)
result = mySession.sql('drop schema if exists unexisting').execute()
process_warnings(result)

# Enables warning generation
mySession.set_fetch_warnings(True)
result = mySession.sql('drop schema if exists unexisting').execute()
process_warnings(result)

Java 代码

// Connect to server
Session mySession = new SessionFactory().getSession("mysqlx://127.0.0.1:33060/test?user=user&password=password");

Schema db = mySession.getSchema("test");

// Create a new collection
Collection myColl = db.createCollection("my_collection");

// Start a transaction
mySession.startTransaction();
try {
    Result res = myColl.add("{\"name\":\"Rohit\", \"age\":18}", "{\"name\":\"Misaki\", \"age\":24}", "{\"name\":\"Leon\", \"age\":39}").execute();

    System.out.println(res.getWarningsCount());

    Iterator<Warning> warnings = res.getWarnings();
    while (warnings.hasNext()) {
        Warning warn = warnings.next();
        System.out.println(warn.getCode() + ", " + warn.getLevel() + ", " + warn.getMessage());
    }

    mySession.commit();
    System.out.println("Data inserted successfully.");
} catch (Exception err) {
    // Rollback the transaction in case of an error
    mySession.rollback();

    // Printing the error message
    System.out.println("Data could not be inserted: " + err.getMessage());
}