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 mysqli_num_rows    (PHP 5) mysqli_num_rows -- 
     Gets the number of rows in a result
     DescriptionProcedural style: mixed  mysqli_num_rows ( mysqli result ) Object oriented style (property): class  mysqli {  mixed num_rows } 
      Returns the number of rows in the result set. 
      
      The use of mysqli_num_rows() depends on whether you use 
      buffered or unbuffered result sets.
      In case you use unbuffered resultsets mysqli_num_rows()
      will not correct the correct number of rows until all the rows in the result 
      have been retrieved.
      返回值
      Returns number of rows in the result set.
      注: 
       If the number of rows is greater than maximal int value, the number
       will be returned as a string.
      
 例例子 1. Object oriented style 
<?php $mysqli = new mysqli("localhost", "my_user", "my_password", "world");
  /* check connection */ if (mysqli_connect_errno()) {     printf("Connect failed: %s\n", mysqli_connect_error());     exit(); }
  if ($result = $mysqli->query("SELECT Code, Name FROM Country ORDER BY Name")) {
      /* determine number of rows result set */     $row_cnt = $result->num_rows;
      printf("Result set has %d rows.\n", $row_cnt);
      /* close result set */     $result->close(); }
  /* close connection */ $mysqli->close(); ?>
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 例子 2. Procedural style 
<?php $link = mysqli_connect("localhost", "my_user", "my_password", "world");
  /* check connection */ if (mysqli_connect_errno()) {     printf("Connect failed: %s\n", mysqli_connect_error());     exit(); }
  if ($result = mysqli_query($link, "SELECT Code, Name FROM Country ORDER BY Name")) {
      /* determine number of rows result set */     $row_cnt = mysqli_num_rows($result);
      printf("Result set has %d rows.\n", $row_cnt);
      /* close result set */     mysqli_free_result($result); }
  /* close connection */ mysqli_close($link); ?>
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 上例将输出: 
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