Introduction to specific functions of using MySQL directly with PHP_PHP Tutorial

We are working on List 1. Access/get.php

<ol class="dp-xml">
<li class="alt"><span><span>＜?php  </span></span></li>
<li class=""><span>function get_user_id( $name )  </span></li>
<li class="alt"><span>{  </span></li>
<li class="">
<span>　$</span><span class="attribute"><font color="#ff0000">db</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">mysql_connect</font></span><span>( 'localhost', 'root', 'password' );  </span>
</li>
<li class="alt"><span>　mysql_select_db( 'users' );  </span></li>
<li class=""><span> </span></li>
<li class="alt">
<span>　$</span><span class="attribute"><font color="#ff0000">res</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">mysql_query</font></span><span>( "SELECT id FROM users WHERE </span><span class="attribute"><font color="#ff0000">login</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">'".$name."'</font></span><span>" );  </span>
</li>
<li class="">
<span>　while( $</span><span class="attribute"><font color="#ff0000">row</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">mysql_fetch_array</font></span><span>( $res ) ) { $</span><span class="attribute"><font color="#ff0000">id</font></span><span> = $row[0]; }  </span>
</li>
<li class="alt"><span> </span></li>
<li class=""><span>　return $id;  </span></li>
<li class="alt"><span>}  </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>var_dump( get_user_id( 'jack' ) );  </span></li>
<li class=""><span>?＞ </span></li>
</ol>

Note that the mysql_connect function is used to enable PHP to use MySQL directly. Also note the query, which uses string concatenation to add the $name parameter to the query.

There are two good alternatives to this technology: the PEAR DB module and the PHP Data Objects (PDO) class. Both provide abstractions from specific database selections. So your code can run without much tweaking on IBM® DB2®, MySQL, PostgreSQL, or any other database you want to connect to.

Another value of using the PEAR DB module and the PDO abstraction layer is that you can use the ? operator in SQL statements. Doing so makes SQL easier to maintain and protects your application from SQL injection attacks.

Alternative code using PEAR DB is shown below.

Listing 2. Access/get_good.php

<ol class="dp-xml">
<li class="alt"><span><span>＜?php  </span></span></li>
<li class=""><span>require_once("DB.php");  </span></li>
<li class="alt"><span> </span></li>
<li class=""><span>function get_user_id( $name )  </span></li>
<li class="alt"><span>{  </span></li>
<li class="">
<span>　$</span><span class="attribute"><font color="#ff0000">dsn</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">'mysql://root:password@localhost/users'</font></span><span>;  </span>
</li>
<li class="alt">
<span>　$</span><span class="attribute"><font color="#ff0000">db</font></span><span> =& DB::Connect( $dsn, array() );  </span>
</li>
<li class=""><span>　if (PEAR::isError($db)) { die($db-＞getMessage()); }  </span></li>
<li class="alt"><span> </span></li>
<li class="">
<span>　$</span><span class="attribute"><font color="#ff0000">res</font></span><span> = $db-＞query( 'SELECT id FROM users WHERE </span><span class="attribute"><font color="#ff0000">login</font></span><span>=?',array( $name ) );  </span>
</li>
<li class="alt">
<span>　$</span><span class="attribute"><font color="#ff0000">id</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">null</font></span><span>;  </span>
</li>
<li class="">
<span>　while( $res-＞fetchInto( $row ) ) { $</span><span class="attribute"><font color="#ff0000">id</font></span><span> = $row[0]; }  </span>
</li>
<li class="alt"><span> </span></li>
<li class=""><span>　return $id;  </span></li>
<li class="alt"><span>}  </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>var_dump( get_user_id( 'jack' ) );  </span></li>
<li class=""><span>?＞ </span></li>
</ol>

Note that all places where PHP uses MySQL directly are eliminated, only the database connection characters in $dsn Except strings. Additionally, we use the $name variable in SQL via the ? operator. The query data is then sent in via the array at the end of the query() method.

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