Log the actual SQL query using ActiveRecord with Yii2?

I'm doing this:

$students = Student::find()->all();
    return $this->render('process', array('students' => $students));

and then this in the view:

foreach($students as $student)
    {
        echo $student->name . ',  ';
        echo $student->getQuizActivitiesCount(); ?> <br /> <?php
    }

i would like to see the sql query being performed. a student "has many" quiz activities, and the query performs perfectly, but i need to see the raw SQL. is this possible?

Method 1

With relations that return yii\db\ActiveQuery instance it's possible to extract the raw SQL query directly in code for example with var_dump().

For example if we have user relation:

/**
 * @return \yii\db\ActiveQuery
 */
public function getUser()
{
    return $this->hasOne(User::className(), ['id' => 'user_id']);
}

You can then var_dump() the raw SQL like that:

var_dump($model->getUser()->prepare(Yii::$app->db->queryBuilder)->createCommand()->rawSql);
exit();

Note that you should call it like that and not $model->user->... (the latter returns User instance).

But in your case it's not possible because count() immediately returns int. You can var_dump() partial query without count(), but I think it's not convenient.

Note that you can use this method for dumping generated SQL of any ActiveQuery instances (not only those that were returned by relation), for example:

$query = User::find()->where(['status' => User::STATUS_ACTIVE]);
var_dump($query->prepare(Yii::$app->db->queryBuilder)->createCommand()->rawSql);
exit();

Method 2

This is much simpler in my opinion and I personally prefer this one when debugging SQL queries.

Yii 2 has built-in debug module. Just add this to your config:

'modules' => [
    'debug' => [
        'class' => 'yii\debug\Module',
    ],
],

Make sure you only have it locally and not on production. If needed, also change allowedIPs property.

This gives you functional panel at the bottom of the page. Find the DB word and click on either count or time. On this page you can view all executed queries and filter them. I usually don't filter them in Grid and use standard browser search to quickly navigate through and find the necessary query (using the table name as keyword for example).

Method 3

Just make an error in query, for example in column name - cityy instead of city. This will result as database exception and then you can instantly see the generated query in error message.

If you want to log all relational queries of ActiveRecord in console application all proposed methods don't help. They show only main SQL on active record's table, \yii\debug\Module works only in browser.

Alternative method to get all executed SQL queries is to log them by adding specific FileTarget to configuration:

'log' => [
    'targets' => [[
        ...
    ], [
        'class' => 'yii\log\FileTarget',
        'logFile' => '@runtime/logs/profile.log',
        'logVars' => [],
        'levels' => ['profile'],
        'categories' => ['yii\db\Command::query'],
        'prefix' => function($message) {
            return '';
        }
    ]]
]

UPDATE

In order to log insert/update/delete queries one should also add yii\db\Command::execute category:

'categories' => ['yii\db\Command::query', 'yii\db\Command::execute']

you can try this, assume you have a query given like:

$query = new Books::find()->where('author=2');
echo $query->createCommand()->sql;

or to get the SQL with all parameters included try:

$query->createCommand()->getRawSql()

In addition to arogachev answer, when you already work with an ActiveQuery object, here is the line I search to view the rawsql.

/* @var $studentQuery ActiveQuery */
$studentQuery = Student::Find();
// Construct the query as you want it
$studentQuery->where("status=3")->orderBy("grade ASC");

// Get the rawsql
var_dump($studentQuery->prepare(Yii::$app->db->queryBuilder)->createCommand()->rawSql);

// Run the query
$studentQuery->all();

when you have a query object you can also use

$query->createCommand()->getRawSql()

to return the Raw SQL with the parameters included or

$query->createCommand()->sql

which will output the Sql with parameters separately.

In order to log/track every/all queries:

extend \yii\db\Connection and override createCommand method, like below:

namespace app\base;

class Connection extends \yii\db\Connection {

    public function createCommand($sql = null, $params = array()) {
        $createCommand = parent::createCommand($sql, $params);
        $rawSql = $createCommand->getRawSql();
         // ########### $rawSql -> LOG IT / OR DO ANYTHING YOU WANT WITH IT
        return $createCommand;
    }
}

Then, simply change your db connection in your db config like below:

'db' => [
        'class' => 'app\base\Connection', //  #### HERE 
        'dsn' => 'pgsql:host=localhost;dbname=dbname',
        'username' => 'uname',
        'password' => 'pwd',
        'charset' => 'utf8',
    ],

Now, you can track/read/... all queries executed by db connection.

Try like,

$query = Yii::$app->db->createCommand()
        ->update('table_name', ['title' => 'MyTitle'],['id' => '1']);

var_dump($query->getRawSql()); die();
$query->execute();

Output:

string 'UPDATE `table_name` 
        SET `title`='MyTitle' WHERE `id`='1'
' (length=204)