📅  最后修改于: 2020-10-16 07:24:05             🧑  作者: Mango
要执行SQL查询,您应该遵循以下步骤-
第1步-创建一个在SiteController称为actionTestDb函数。
public function actionTestDb(){
// return a set of rows. each row is an associative array of column names and values.
// an empty array is returned if the query returned no results
$users = Yii::$app->db->createCommand('SELECT * FROM user LIMIT 5')
->queryAll();
var_dump($users);
// return a single row (the first row)
// false is returned if the query has no result
$user = Yii::$app->db->createCommand('SELECT * FROM user WHERE id=1')
->queryOne();
var_dump($user);
// return a single column (the first column)
// an empty array is returned if the query returned no results
$userName = Yii::$app->db->createCommand('SELECT name FROM user')
->queryColumn();
var_dump($userName);
// return a scalar value
// false is returned if the query has no result
$count = Yii::$app->db->createCommand('SELECT COUNT(*) FROM user')
->queryScalar();
var_dump($count);
}
上面的示例显示了从数据库获取数据的各种方式。
步骤2-转到地址http:// localhost:8080 / index.php?r = site / test-db ,您将看到以下输出。
要创建带有参数的SQL命令,应始终使用绑定参数的方法来防止SQL注入。
步骤1-以这种方式修改actionTestDb方法。
public function actionTestDb() {
$firstUser = Yii::$app->db->createCommand('SELECT * FROM user WHERE id = :id')
->bindValue(':id', 1)
->queryOne();
var_dump($firstUser);
$params = [':id' => 2, ':name' => 'User2'];
$secondUser = Yii::$app->db->createCommand('SELECT * FROM user WHERE
id = :id AND name = :name')
->bindValues($params)
->queryOne();
var_dump($secondUser);
//another approach
$params = [':id' => 3, ':name' => 'User3'];
$thirdUser = Yii::$app->db->createCommand('SELECT * FROM user WHERE
id = :id AND name = :name', $params)
->queryOne();
var_dump($thirdUser);
}
在上面的代码中-
bindValue() -绑定单个参数值。
bindValues() -绑定多个参数值。
步骤2-如果转到地址http:// localhost:8080 / index.php?r = site / test-db ,您将看到以下输出。
对于INSERT,UPDATE和DELETE查询,可以调用insert(),update()和delete()方法。
步骤1-以这种方式修改actionTestDb方法。
public function actionTestDb() {
public function actionTestDb(){
// INSERT (table name, column values)
Yii::$app->db->createCommand()->insert('user', [
'name' => 'My New User',
'email' => 'mynewuser@gmail.com',
])->execute();
$user = Yii::$app->db->createCommand('SELECT * FROM user WHERE name = :name')
->bindValue(':name', 'My New User')
->queryOne();
var_dump($user);
// UPDATE (table name, column values, condition)
Yii::$app->db->createCommand()->update('user', ['name' => 'My New User
Updated'], 'name = "My New User"')->execute();
$user = Yii::$app->db->createCommand('SELECT * FROM user WHERE name = :name')
->bindValue(':name', 'My New User Updated')
->queryOne();
var_dump($user);
// DELETE (table name, condition)
Yii::$app->db->createCommand()->delete('user', 'name = "My New User
Updated"')->execute();
$user = Yii::$app->db->createCommand('SELECT * FROM user WHERE name = :name')
->bindValue(':name', 'My New User Updated')
->queryOne();
var_dump($user);
}
}
步骤2-在Web浏览器的地址栏中输入URL http:// localhost:8080 / index.php?r = site / test-db ,您将看到以下输出。