Summary of the differences in PDO database operations between PHP 5.1.* and 5.2.*_PHP Tutorial

介绍
今天发现php5.1.*和php5.2.*在数据库预编译代码执行的时候出现差异。
预编译优点
1.使用占位符，避免逐字输入数据到SQL中。自动处理引号和反斜线等字符的转义——增加安全性。
2.预先“准备”一条语句，然后在每次执行时绑定不同值达到重用的目的。——常用于以后被多次执行的语句。
3.可读性强。

代码
数据库连接代码都一样.

复制代码 代码如下:

$protol = 'mysql:host=localhost;dbname=test';
$username = 'monty';
$passwd = '0818';
$dbh = new PDO($protol, $username, $passwd);

以下是一些测试。注意里面的SQL和for或者foreach语句!
测试1(用key值进行绑定)

复制代码 代码如下:

$stmt = $dbh->prepare('select * from t1 where name=:name');
$params = array();
$params['name'] = 'rentao';
foreach($params as $k=>$v){
$stmt->bindParam($k, $v);
}
$stmt->execute();
$item = array();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
var_dump($row);
}
$stmt = null;
$dbh = null;

结论:

PHP 5.1.*	PHP 5.2.*
执行正常	执行正常
$params['name'] = 'rentao' 和$params[':name']='rentao'这两个都能执行，说明不受“：”限制。

测试2(数字下标去绑定，但是绑定的起始参数是1)——":key"在php5.2.*上不能用数字下标绑定

复制代码 代码如下:

$stmt = $dbh->prepare('select * from t1 where name=:name limit 2');
$params = array();
$params[] = 'rentao';// 这里加不加":"都能成功执行


for($i=0,$iLen = count($params); $i $k = $i+1;
$stmt->bindParam($k, $params[$i]);
}
echo "HERE1\n";
$stmt->execute();
echo "HERE2\n";

$item = array();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
var_dump($row);
}
$stmt = null;
$dbh = null;

结论：

php 5.1.*	PHP 5.2.*
执行正常	出现错误:“PHP Warning:  PDOStatement::execute(): SQLSTATE[HY093]: Invalid parameter number: parameter was not defined”
如果把":name"改成"?"，那么两个版本都可以顺利进行。
不能同时使用两种符号。如 select * from t2 where name=? limit :page

测试3(limit绑定:page)

复制代码 代码如下:

$stmt = $dbh->prepare('select * from t2 where name=:name limit :page');
$params = array();
$params['name'] = 'rentao';// 这里加不加":"都能成功执行
$params['page'] = 2;
foreach($params as $k=>$v){
$stmt->bindParam($k, $v);
}
$stmt->execute();
echo "HERE1\n";
$item = array();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
var_dump($row);
}
echo "HERE2\n";
$stmt = null;
$dbh = null;

结论:

PHP 5.1.*	PHP 5.2.*
执行到$stmt->execute()时，进程一直处于等待状态中	执行正常:打印不出结果

Test 4 (precompile operation under limit: page) - use the "?" mechanism to run

Copy code The code is as follows:

$stmt = $dbh->prepare('select * from t2 where name=? limit ?');
$params = array();
$params[] = 'rentao';
$params[] = 2;
for($i=0,$iLen = count($params); $i $k = $i+1;
$stmt->bindParam($k, $params[$i]);
}
$stmt->execute();
$item = array ();
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
var_dump($row);
}
$stmt = null;
$ dbh = null;

PHP 5.1.*	PHP 5.2.*
执行正常	执行正常:打印不出结果

Test 5---order by)

PHP 5.1.*	PHP 5.2.*
打印出结果，但未按order by进行排序	执行正常:打印不出结果

Summary
When PHP uses PDO for database pre-compilation operations, try to avoid using limit, order by, group by for pre-compilation processing. We try to use unified standards for bind variables, otherwise we use "?", otherwise we use ":key".

Useful command, I tested it on php5.1.*. After the test, I transferred the file to the php5.2.* server through scp.

Copy Code The code is as follows:

scp -P9888 index.php rentao@192.168.10.4:/home/rentao

http://www.bkjia.com/PHPjc/325264.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/325264.htmlTechArticleIntroduction Today I found that there are differences between php5.1.* and php5.2.* when the database precompiled code is executed. . Advantages of precompilation 1. Use placeholders to avoid entering data into SQL verbatim. Automatically process quotes...