调用未定义的方法 mysqli_result::fetch()

我能够从中获取数据get_result()使用任何fetch_assoc(), fetch_all()， ...， 和fetch_row()但是当我尝试使用简单的fetch()只是，我收到这个错误

未捕获的错误：调用未定义的方法 mysqli_result::fetch()

这是因为使用get_result()？或者我在下面的代码中遗漏了其他内容

$stmt = $conn->prepare($SQL);
$stmt->bind_param("s", $date);
$stmt->execute();
$result = $stmt->get_result();
//$row = $result->fetch_assoc();
//$row = $result->fetch_all();
//$row = $result->fetch_row();
$row = $result->fetch();

变量$stmt是一个对象mysqli_stmt https://secure.php.net/manual/en/class.mysqli-stmt.php班级。这个类有一个方法叫做fetch() https://www.php.net/manual/en/mysqli-stmt.fetch.php它返回一个布尔值（真/假）。它仅与bind_result() https://www.php.net/manual/en/mysqli-stmt.bind-result.php

$stmt = $conn->prepare('SELECT myCol, myOtherCol FROM myTable WHERE dt=?');
$stmt->bind_param("s", $date);
$stmt->execute();
// The columns in SQL will be bound to the PHP variables
$stmt->bind_result($variable1, $variable2);
while ($stmt->fetch()) {
    // This will fetch each record from the prepared statement one by one
    printf ("myCol is %s and myOtherCol is %s\n", $variable1, $variable1);
}

$stmt->get_result() https://www.php.net/manual/en/mysqli-stmt.get-result.php返回一个类的对象mysqli_result https://www.php.net/manual/en/class.mysqli-result.php（顺便说一下，可以使用foreach）。这个类有不同的方法，但它没有fetch() method.

• fetch_all() https://www.php.net/manual/en/mysqli-result.fetch-all.php返回一个数组的数组。顾名思义，它会立即返回结果集中的所有记录。

  $result = $stmt->get_result();
  $allRecords = $result->fetch_all(\MYSQLI_ASSOC);
  echo json_encode($allRecords);
  

• fetch_array() https://www.php.net/manual/en/mysqli-result.fetch-array.php将每条记录一一返回为一维数组

  $row = $result->fetch_array();
  printf("%s (%s)\n", $row["myCol"], $row["myOtherCol"]);
  

• fetch_assoc() https://www.php.net/manual/en/mysqli-result.fetch-assoc.php相当于fetch_array(\MYSQLI_ASSOC)
• fetch_row() https://www.php.net/manual/en/mysqli-result.fetch-row.php相当于fetch_array(\MYSQLI_NUM)
• fetch_object() https://www.php.net/manual/en/mysqli-result.fetch-object.php将每条记录作为对象一一返回。

  $row = $result->fetch_object();
  printf("%s (%s)\n", $row->myCol, $row->myOtherCol);
  

但是，为了简单起见，您可以循环mysqli_result直接将每一行作为关联数组。

foreach($stmt->get_result() as $row) {
    printf("%s (%s)\n", $row["myCol"], $row["myOtherCol"]);
}