PHP中mysqli_num_rows怎么使用

mysqli_num_rows函数用于获取结果集中的行数。使用方法如下：

1.创建数据库连接：

$conn = mysqli_connect("localhost", "username", "password", "database_name"); if (!$conn) {     die("连接失败: " . mysqli_connect_error()); } 

2.执行SQL查询并获取结果集：

$sql = "SELECT * FROM table_name"; $result = mysqli_query($conn, $sql); 

3.使用mysqli_num_rows函数获取结果集中的行数：

$row_count = mysqli_num_rows($result); echo "行数：" . $row_count; 

完整示例代码如下：

$conn = mysqli_connect("localhost", "username", "password", "database_name"); if (!$conn) {     die("连接失败: " . mysqli_connect_error()); }  $sql = "SELECT * FROM table_name"; $result = mysqli_query($conn, $sql); $row_count = mysqli_num_rows($result); echo "行数：" . $row_count;  mysqli_close($conn); 

注意：在使用mysqli_num_rows函数之前，需要确保已经执行了SQL查询并获取了结果集。