mysqli_query和mysql_query的一点区别

来源：互联网发布：dijkstra算法原理编辑：程序博客网时间：2024/06/05 08:37

mysqli是php5提供的新函数库，i表示改进（improve），其执行速度要比mysql_query更快。一般现在php在5或者5以上的版本之中默认支持extension=php_mysql.dll和extension=php_mysqli.dll。

mysql.dll查询方式可以理解为过程化的查询，如下：

$conn=mysql_connect('localhost','user','password'); //连接mysql数据库

mysql_select_db('databse'); //选择数据库

$result=mysql_query('select * from table_name'); //mysql_query有两个参数mysql_query(query,connection),第二个参数可选，指明打开连接的名称。

$rzt=mysql_fetch_assoc($qry)，$qry是必须的，代表数据指针，该数据指针是从mysql_query()返回的结果集。利用循环语句输出所有语句。

mysqli.dll的查询存在两种方式(网上找到的两个很好的例子)：

1、对象方式：

<?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();

}

/* Create table doesn't return a resultset */

if ($mysqli->query("CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {

printf("Table myCity successfully created.\n");

}

/* Select queries return a resultset */

if ($result = $mysqli->query("SELECT Name FROM City LIMIT 10")) {

printf("Select returned %d rows.\n", $result->num_rows);

/* free result set */

$result->close();

}

/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */

if ($result = $mysqli->query("SELECT * FROM City", MYSQLI_USE_RESULT)) {

/* Note, that we can't execute any functions which interact with the server until result set was closed. All calls will return an 'out of sync' error */

if (!$mysqli->query("SET @a:='this will not work'")) {

printf("Error: %s\n", $mysqli->error);

}

$result->close();

}

$mysqli->close();
?>

2、过程化方式：

<?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();
}

/* Create table doesn't return a resultset */
if (mysqli_query($link, "CREATE TEMPORARY TABLE myCity LIKE City") === TRUE) {
printf("Table myCity successfully created.\n");
}

/* Select queries return a resultset */
if ($result = mysqli_query($link, "SELECT Name FROM City LIMIT 10")) {
printf("Select returned %d rows.\n", mysqli_num_rows($result));

/* free result set */
mysqli_free_result($result);
}

/* If we have to retrieve large amount of data we use MYSQLI_USE_RESULT */
if ($result = mysqli_query($link, "SELECT * FROM City", MYSQLI_USE_RESULT)) {

/* Note, that we can't execute any functions which interact with the server until result set was closed. All calls will return an 'out of sync' error */
if (!mysqli_query($link, "SET @a:='this will not work'")) {
printf("Error: %s\n", mysqli_error($link));
}
mysqli_free_result($result);
}

mysqli_close($link);
?>

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