php语法中mysql数据库如何实现链接、查询、插入、更新

1、连接数据库

$host = 'localhost';
$username = 'root';
$password = 'password';
$dbname = 'webnet';
 
// 创建数据库连接
$db = new mysqli($host, $username, $password, $dbname);
 
// 检查连接是否成功
if ($db->connect_error) {
  die("连接失败: " . $db->connect_error);
} else {
  echo "连接成功！";
}

2、查询数据

$sql = "SELECT * FROM table";
$result = $db->query($sql);
 
if ($result->num_rows > 0) {
  while ($row = $result->fetch_assoc()) {
    echo "id: " . $row["id"] . " - Name: " . $row["name"] . "
";
  }
} else {
  echo "没有数据";
}

3、插入数据

$name = '小米';
$school = '清北';
 
$sql = "INSERT INTO table (name, school) VALUES ('$name', '$school')";
 
if ($db->query($sql) === TRUE) {
  echo "新记录插入成功！";
} else {
  echo "Error: " . $sql . "<br>" . $db->error;
}

4、更新数据

$id = 10;
$newName = 'Jane Doe';
 
$sql = "UPDATE table SET name='$newName' WHERE id=$id";
 
if ($db->query($sql) === TRUE) {
  echo "记录更新成功！";
} else {
  echo "Error: " . $sql . "<br>" . $db->error;
}