mysql绑定变量的使用方法

<?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();
}

$city = "Amersfoort";

/* create a prepared statement */
if ($stmt = $mysqli->prepare("SELECT District FROM City WHERE Name=?")) {

    /* bind parameters for markers */
    $stmt->bind_param("s", $city);

    /* execute query */
    $stmt->execute();

    //下面的变量为查询表中的字段命名的变量
    $stmt->bind_result($district);

    /* fetch value */
    $stmt->fetch();

    printf("%s is in district %s\n", $city, $district);

    /* close statement */
    $stmt->close();
}

/* close connection */
$mysqli->close();
?>

 上面的是mysql中查询的变量帮定使用方法

在mysql的查询中需要将语句先进行解析处理再进行缓存处理，如果在解析的过程中判断该语句已经执行过的话则直接执行，不会再次进行解析

如下面的语句

select * from flight where fnum='MU5674'

select * from fllight where fnum='MU5655'

可能因为一个变量的原因就需要mysql的重新解析 这时就需要mysql的重新解析

如果写成

select * from flight where fnum=?

则此时的效果就不一样了  执行的结果可以通过

mysql> show profiles;
+----------+------------+-------------------------------------------+
| Query_ID | Duration   | Query                                     |
+----------+------------+-------------------------------------------+
|       31 | 0.00007200 | set @s:=3                                 |
|       32 | 0.01539800 | select count(*) from io_01 where c1 = @s  |
|       33 | 0.01528700 | select count(*) from io_01 where c1 = @s  |
|       34 | 0.01539700 | select count(*) from io_01 where c1 = @s  |
|       35 | 0.01587500 | select count(*) from io_01 where c1 = @s  |
|       36 | 0.01508000 | select count(*) from io_01 where c1 = @s  |
|       37 | 0.01512300 | select count(*) from io_01 where c1 = @s  |
|       38 | 0.01506700 | select count(*) from io_01 where c1  =  3 |
|       39 | 0.00022400 | select count(*) from io_01 where c1  =  3 |
|       40 | 0.00021400 | select count(*) from io_01 where c1  =  3 |
|       41 | 0.00004000 | select count(*) from io_01 where c1  =  3 |
|       42 | 0.00022300 | select count(*) from io_01 where c1  =  3 |
|       43 | 0.00023800 | select count(*) from io_01 where c1  =  3 |
|       44 | 0.00022500 | select count(*) from io_01 where c1  =  3 |
|       45 | 0.00004000 | select count(*) from io_01 where c1  =  3 |
+----------+------------+-------------------------------------------+
15 rows in set (0.00 sec)

来查询执行的结果 ！

以下是mysql绑定变量在增删改方面的运用

<?php 
                $mysqli=new mysqli("localhost", "root", "123321", "test"); 
 
                $sql1="set @@profiling=1"; 
                $result1=$mysqli->query($sql1); 
 
                //准备好一条语句放到服务器中，插入语句 
                $sql="insert into t(name,sex) values (?,?)"; 
 
                $stmt=$mysqli->prepare($sql); 
 
                //给占位符号每个?号传值（绑定参数） i    d    s    b    
                $stmt->bind_param("si", $name, $sex); 
 
                $name="andy"; 
                $sex=0; 
 
                //执行 
                $stmt->execute(); 
 
 
                $name="mandy"; 
                $sex=1; 
 
                //执行 
                $stmt->execute(); 
 
 
                $name="michael"; 
                $sex=0; 
 
                //执行 
                $stmt->execute(); 
 
 
                $name="happy"; 
                $sex=1; 
 
                //执行 
                $stmt->execute(); 
 
                $name="php"; 
                $sex=1; 
 
                //执行 
                $stmt->execute(); 
 
 
                $name="mysql"; 
                $sex=1; 
 
                //执行 
                $stmt->execute(); 
 
                $name="linux"; 
                $sex=1; 
 
                //执行 
                $stmt->execute(); 
 
                $name="oracle"; 
                $sex=1; 
 
                //执行 
                $stmt->execute(); 
 
                $name="unix"; 
                $sex=1; 
 
                //执行 
                $stmt->execute(); 
 
                $name="cisco"; 
                $sex=1; 
 
                //执行 
                $stmt->execute(); 
 
 
                $stmt->close(); 
 
 
                $sql2="show profiles"; 
                $result2=$mysqli->query($sql2); 
 
                echo '<table border=1 align="center" width=800>'; 
                while($rows=$result2->fetch_assoc()){ 
                                echo '<tr align="center">'; 
                                foreach($rows as $value){ 
                                                echo '<td>' . $value    . '</td>'; 
                                } 
                                echo '</tr>'; 
                                $i=0; 
                                $i=$i+$rows["Duration"]; 
                } 
                echo '</table>'; 
                echo $i; 
?>