$customers = Customer::find()->where($cond)->all();

// SQL: (type = 1) AND (status = 2).  
$cond = ['type' => 1, 'status' => 2]   
// SQL:(id IN (1, 2, 3)) AND (status = 2)  
$cond = ['id' => [1, 2, 3], 'status' => 2]   
//SQL:status IS NULL  
$cond = ['status' => null]

//SQL:`id=1 AND id=2`  
$cond = ['and', 'id=1', 'id=2']  
//SQL:`type=1 AND (id=1 OR id=2)`  
$cond = ['and', 'type=1', ['or', 'id=1', 'id=2']]  
//SQL:`type=1 AND (id=1 OR id=2)` //此寫法'='可以換成其他操作符，例：in like != >=等  
$cond = [  
    'and',  
    ['=', 'type', 1],  
    [  
        'or',  
        ['=', 'id', '1'],  
        ['=', 'id', '2'],  
    ]  
]

/SQL:`(type IN (7, 8, 9) OR (id IN (1, 2, 3)))`  
$cond = ['or', ['type' => [7, 8, 9]], ['id' => [1, 2, 3]]

//SQL:`NOT (attribute IS NULL)`  
$cond = ['not', ['attribute' => null]]

//SQL:`id BETWEEN 1 AND 10`  
$cond = ['between', 'id', 1, 10]

//SQL:`id IN (1, 2, 3)`  
$cond = ['in', 'id', [1, 2, 3]] or $cond = ['id'=>[1, 2, 3]]

//IN條件也適用于多字段  
$cond = ['in', ['id', 'name'], [['id' => 1, 'name' => 'foo'], ['id' => 2, 'name' => 'bar']]]  
//也適用于內嵌sql語句  
$cond = ['in', 'user_id', (new Query())->select('id')->from('users')->where(['active' => 1])]

//SQL:`name LIKE '%tester%'`
$cond = ['like', 'name', 'tester']
//SQL:`name LIKE '%test%' AND name LIKE '%sample%'`
$cond = ['like', 'name', ['test', 'sample']]
//SQL:`name LIKE '%tester'`
$cond = ['like', 'name', '%tester', false]

//SQL:EXISTS (SELECT "id" FROM "users" WHERE "active"=1)
$cond = ['exists', (new Query())->select('id')->from('users')->where(['active' => 1])]

//SQL:`id >= 10`
$cond = ['>=', 'id', 10] 
//SQL:`id != 10`
$cond = ['!=', 'id', 10]