PHP mysqli_num_rows Error Solutions

1 year ago
Isabella Edwards
2 minutes

In PHP, the mysqli_num_rows function is used to get the number of rows returned by a query. If this function gives an error, it is usually due to incorrect parameters being passed or errors in the query statement.

The solution is as follows:

  1. Ensure that you are properly connected to the database and have obtained a valid connection object. You can use the mysqli_connect function to connect to the database.
  2. Make sure you have executed the query statement and that the query results are saved in a valid result set object. You can use the mysqli_query function to execute the query statement and store the results in a variable.
  3. Before calling the mysqli_num_rows function, make sure you have checked if the query operation was successful. You can use the mysqli_error function to check for any errors that may have occurred.
  4. Make sure you pass the correct parameter when calling the mysqli_num_rows function. The function takes a result set object as a parameter.

Here is an example code that demonstrates how to correctly use the mysqli_num_rows function:

// 连接到数据库
$conn = mysqli_connect("localhost", "username", "password", "database");

// 检查连接是否成功
if (!$conn) {
    die("连接失败: " . mysqli_connect_error());
}

// 执行查询语句
$result = mysqli_query($conn, "SELECT * FROM table");

// 检查查询是否成功
if (!$result) {
    die("查询错误: " . mysqli_error($conn));
}

// 获取查询结果的行数
$numRows = mysqli_num_rows($result);

// 输出查询结果的行数
echo "查询结果的行数为: " . $numRows;

// 关闭数据库连接
mysqli_close($conn);

Please note that the above examples are for reference only and actual results may vary depending on database configurations and query statements. You may need to make adjustments accordingly based on your specific situation.

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