Detailed explanation of how to use php PDO_PHP tutorial-PHP Tutorial-php.cn

This article will give you a detailed introduction to how to use php PDO. You are welcome to refer to it. Friends who need to know more can save this article.

PDO::exec

The returned type is int, indicating the number of items that affect the result.

PDOStatement::execute

The returned value is boolean, true indicates successful execution, false indicates execution failure.
These two usually appear in:

The code is as follows

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代码如下	复制代码
$rs0 = $pdo->exec($sql); $pre = $pdo->prepare($sql); $rs1 = $pre->execute();

$rs0 = $pdo->exec($sql);

$pre = $pdo->prepare($sql);
$rs1 = $pre->execute();

Generally, you can use the value of $rs0 to determine whether the SQL execution is successful or not. If the value is false, it means that the SQL execution failed, 0 means no changes, and a value greater than 0 means how many records were affected.

However, $rs1 can only return whether the SQL execution is successful or not. If you need to get the number of affected records, you need to use $pre->rowCount();

I personally like to use MySQL, so I have these two lines in my extensions.ini

extension=pdo.so

extension=pdo_mysql.so

代码如下	复制代码
define('DB_NAME','test'); define('DB_USER','test'); define('DB_PASSWD','test'); define('DB_HOST','localhost'); define('DB_TYPE','mysql'); $dbh = new PDO(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASSWD);

Then in the program, we need to declare PDO?⒍? Tombδ?/p>

Code: [Select]

The code is as follows

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define('DB_NAME','test');

define('DB_USER','test');

define('DB_PASSWD','test');

define('DB_HOST','localhost');

define('DB_TYPE','mysql');

$dbh = new PDO(DB_TYPE.':host='.DB_HOST.';dbname='.DB_NAME, DB_USER, DB_PASSWD);

The constant setting used in this article is my personal habit. You don’t have to be like me? Trouble

When operating like the above, $dbh itself represents the PDO connection

代码如下	复制代码
$sql = 'select * from test'; foreach ( $dbh->query($sql) as $value) { echo $value[col]; };

So what? Use PDO?

The first formula is the lazy method query

Don’t think about anything, just use the query function as usual

Code: [Select]

The code is as follows

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$sql = 'select * from test';

foreach ( $dbh->query($sql) as $value)

{

echo $value[col];

代码如下	复制代码
$sth = $dbh->prepare('update db set zh_CN= :str where SN=:SN'); $sth->bindParam(':str',$str,PDO::PARAM_STR,12); $sth->bindParam(':SN',$SN); $sth->execute();

};

The second formula is the automatic bring-in method prepare After using PDO, I prefer to use the prepare function to perform actions The advantage of prepare is that you can write the SQL code first and automatically bring in the data we want later I think the biggest advantage of this is that it can reduce many security issues compared to using query directly First, we use prepare to set the SQL code, and then use bindparm to perform the setting action Code: [Select]

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$sth = $dbh->prepare('update db set zh_CN= :str where SN=:SN'); $sth->bindParam(':str',$str,PDO::PARAM_STR,12); $sth->bindParam(':SN',$SN); $sth->execute();

Please pay attention to :str and :SN in the article. When we use the bindParam function, we can use :word to specify the part that the system needs to apply. For example, we use :str and :SN to specify
As for the actual content, bindParam can also specify the type we want to input.

首先我们先看:str 的指定，:str 由於我确定资料是属於文字，因此利用PD::PARAM_STR 来告诉程式“这个是字串哟”，并且给一个范围，也就是长度是12个Bit.
We can also avoid that complexity, like :SN. Although it is also specified using bindParam, we omit the type and length. PHP will use the default type of the variable.

Finally, use $sth->execute(); to perform the execution action.

Basically it’s not difficult, it can even be said to be very simple!

If you have a large amount of data that needs to be applied repeatedly, you can desperately reuse bindParam to specify, such as my :str and :SN. If there are ten pieces of data, I can also add it directly to the data like this Library

Code: [Select]

The code is as follows

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代码如下	复制代码
$sth = $dbh->prepare('insert into db ("zh_CN","zh_TW")values(:str , :SN'); foreach ($array => $value ) { $sth->bindParam(':str',$value[str],PDO::PARAM_STR,12); $sth->bindParam(':SN',$value[SN]); $sth->execute(); }

$sth = $dbh->prepare('insert into db ("zh_CN","zh_TW")values(:str , :SN');

foreach ($array => $value )
{

$sth->bindParam(':str',$value[str],PDO::PARAM_STR,12);

$sth->bindParam(':SN',$value[SN]);

$sth->execute();

}

Even strong people like my friend... write all possible SQLs in one file, and then all the subsequent procedural SQL parts will be brought in with variables!

代码如下	复制代码
$sth = $dbh->prepare('select * from db where SN = :SN'); $sth->bindParam(':SN',$value[SN]); $sth->execute(); while($meta = $sth->fetch(PDO::FETCH_ASSOC)) { echo $meta["name"]; }

Anyway, the data can be applied in ready-made ways!

Then, if you use prepare to select, of course the keywords can also be specified using :word as above

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$sth = $dbh->prepare('select * from db where SN = :SN');

$sth->bindParam(':SN',$value[SN]);
$sth->execute();
while($meta = $sth->fetch(PDO::FETCH_ASSOC))

{

echo $meta["name"];
}

This? The new one is fetch, which has the same meaning as mysql_fetch_row()
But in fetch() we found an extra PDO::FETCH_ASSOC
fetch() provides many ways to obtain data, and PDO::FETCH_ASSOC refers to returning the field name and value of the next data For example, in the above example, use $meta to obtain the data returned by fetch. At this time

The element name of $meta is the field name of the database, and the content is of course the value itself

代码如下	复制代码
$sth = $dbh->prepare('select * from db where SN = :SN'); $sth->bindParam(':SN',$value[SN]); $sth->execute(); if ($sth->errorCode()) { echo "有错误！有错误！"; print_r($sth->errorInfo()); }

This is different from when you use mysql_fetch_row(), because in addition to the field name, mysql_fetch_row() will also follow the sequence In addition to the field, the element name is given to an element based on a serial number. Doesn't PDO have it? Of course, as long as PDO::FETCH_ASSOC is changed to PDO::FETCH_BOTH, the usage is the same as mysql_fetch_row(). How to troubleshoot Debugging is an eternal pain for all programmers. How do we debug using PDO? In fact, PDO already provides two very convenient functions errorInfo() and errorCode() Usage is also very simple. Whenever we use execute() to execute, if there is an error Then there will be content in errorInfo() and errorCode() This is how we can do it.... Code: [Select]

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$sth = $dbh->prepare('select * from db where SN = :SN'); $sth->bindParam(':SN',$value[SN]); $sth->execute(); if ($sth->errorCode()) { echo "There is an error! There is an error!"; print_r($sth->errorInfo()); }

And $sth->errorInfo() will be an array, this array has three values
0 is SQLSTATE error code
1 The error code returned by the Driver you are using
2 Error message returned by the Driver you are using