PHP错误 - mysqli_fetch_assoc返回Null [重复]

Question

This question already has an answer here:

• How do I get PHP errors to display? 27 answers
• mysqli_fetch_assoc() expects parameter / Call to a member function bind_param() errors. How to get the actual mysql error? 1 answer
• How to make mysqli throw exceptions using MYSQLI_REPORT_STRICT? 2 answers

I am new to php and mysql. I am trying to read data from a table. Here's the code:

<?php
$conn = mysqli_connect("localhost", "root", "MyPass", "MyDB");
$sql = "SELECT Foo FROM MyTable";
$result = mysqli_query($conn, $sql);
$row = mysqli_fetch_assoc($result);
if($row == null)
{
  echo'mysqli_fetch_assoc returned null';
}
else
{
  echo row['Foo'];
}
?>

And here's the table:

+---------+
|   Foo   |
+---------+
|       5 |
|       5 |
|       5 |
+---------+

`

Right now the code prints out "mysqli_fetch_assoc returned null", showing that something is wrong. Does anyone know what's causing the error? How can I fix it?

</div>

Answer 1

I think you should mysqli_fetch_assoc inside while loop

Like this.

<?php
$conn = mysqli_connect("localhost", "root", "MyPass", "MyDB");
$sql = "SELECT Foo FROM MyTable";
if ($result = mysqli_query($conn, $sql)) {
  while ($row = mysqli_fetch_assoc($result)) {
    if($row == null)
    {
      echo'mysqli_fetch_assoc returned null';
    }
    else
    {
      echo row['Foo'];
    }
  }
  mysqli_free_result($result);
}

mysqli_close($conn)
?>