通过PHP你可以轻松的连接到数据库，请求数据并将其显示在你的web站点中，甚至修改数据库中的数据。MySQL是一种很流行的数据库，并且在互联网中有许多有关PHP与MySQL的教程。MySQL是免费的，这一点也许就吸引了不少人。由于其广泛应用，我就不想在这里赘述MySQL的使用方法了。Oracle被大量在企业应用中采用，因此我们就利用Oracle来介绍PHP与数据库的连接。我们当然不会提及Oracle数据库的设计原理，原因是这已经超出了我们的讨论范围。

　　PHP提供了两套函数与Oracle连接，分别是ORA_和OCI函数。其中ORA_函数略显陈旧。OCI函数更新据说更好一些。两者的使用语法几乎相差无几。你的PHP安装选项应该可以支持两者的使用。

　　连接

<　? if ($conn=Ora_Logon("user@TNSNAME","password"))
{ echo "SUCCESS ! Connected to database ";
}else
{echo "Failed :-( Could not connect to database ";}
Ora_Logoff($conn);
phpinfo();
?>

　　以上代码使用TNSNAME（在你的tnsnames.ora文件中指明）定义的Oracle数据库名称、用户名称和密码连接数据库。在成功连接的基础上，ora_logon函数返回一个非零的连接ID并储存在变量$conn中。

　　查询

　　假设与数据库已经连接就绪，下面我们就来实际的应用对数据库的查询。下面的代码演示了一个连接并查询的典型例子：

function printoraerr($in_cur)
{
// 检查Oracle是否出错
// 如果存在错误则显示
// 当指针被激活时每次请求Oracle后调用该函数
if(ora_errorcode($in_cur))
echo "Oracle code - ".ora_error($in_cur)." ";
return;
}
if (!($conn=ora_logon("user@TNSNAME","password")))
{echo "Connection to database failed ";
exit;
}
echo "Connected as connection - $conn ";
echo "Opening cursor ... ";
$cursor=ora_open($conn); printoraerr($cursor);
echo "Opened cursor - $cursor ";
$qry="select user,sysdate from dual";
echo "Parsing the query $qry ... ";
ora_parse($cursor,$qry,0); printoraerr($cursor);
echo "Query parsed ";
echo "Executing cursor ... ";
ora_exec($cursor); printoraerr($cursor);
echo "Executed cursor ";
echo "Fetching cursor ... ";
while(ora_fetch($cursor))
{
$user=ora_getcolumn($cursor,0); printoraerr($cursor);
$sysdate=ora_getcolumn($cursor,1); printoraerr($cursor);
echo " row = $user, $sysdate ";
}
echo "Fetched all records ";
echo "Closing cursor ... ";
ora_close($cursor);
echo "Closed cursor ";
echo "Logging off from oracle... ";
ora_logoff($conn);
echo "Logged off from oracle ";
?>

　　显示结果

　　以下代码演示了怎样查询数据库并将结果输出：

function printoraerr($in_cur, $conn)
{
// 检查Oracle是否出错
// 如果存在错误则显示
// 当指针被激活时每次请求Oracle后调用该函数
// If it encountered an error, we exit immediately
if(ora_errorcode($in_cur))
{echo "Oracle code - ".ora_error($in_cur)." n";
ora_logoff($conn);
exit;
}
return;
}

function exequery($w_qry,$conn)
{
$cursor=ora_open($conn); printoraerr($cursor,$conn);
ora_parse($cursor,$w_qry,0); printoraerr($cursor,$conn);
ora_exec($cursor); printoraerr($cursor,$conn);
$numrows=0;
$w_numcols=ora_numcols($cursor);
// 显示头部
echo " ";
for ($i=0;$i<$w_numcols;$i++)
{
$align=(ora_columntype($cursor,$i)=="NUMBER")?"RIGHT":"LEFT";
echo " ".ora_columnname($cursor,$i)." ";
}
echo " ";
while(ora_fetch($cursor))
{
echo " ";
for ($i=0;$i<$w_numcols;$i++)
{
$align=(ora_columntype($cursor,$i)=="NUMBER")?"RIGHT":"LEFT";
if(ora_columntype($cursor,$i)=="LONG")
echo " ".
ora_getcolumn($cursor,$i)." ";
else
echo " ".ora_getcolumn($cursor,$i)." ";
printoraerr($cursor,$conn);
}
$numrows++;
echo " ";
}
if ($numrows==0)
echo " Query returned no records ";
else
{
echo " ";
echo " Count ";
echo " $numrows ";
echo " ";
}
echo " ";
ora_close($cursor);
return;
}
// 主程序
if(!($conn=ora_logon("user@SID","password")))
{
echo "Error: Cannot connect to database ";
exit;
}
$qry="SELECT
deptno "Dept"
,empno "Emp"
,empnm "Name"
,salary "Salary"
FROM
employee
ORDER BY 1,2";
exequery($qry);
ora_logoff($conn);
?>


　　基于HTTP的Oracle登录

　　将以下代码加在PHP页面代码之前以确认Oracle登录。注意你必须正确设定$ SID。

if(!isset($PHP_AUTH_USER))
{
Header("WWW-authenticate: basic realm="$SID"");
Header("HTTP/1.0 401 Unauthorized");
$title="Login Instructions";
echo "
You are not authorized to enter the site
";
exit;
}
else
{
if (!($conn=ora_logon("$PHP_AUTH_USER@$SID",$PHP_AUTH_PW)))
{Header("WWW-authenticate: basic realm="$SID"");
Header("HTTP/1.0 401 Unauthorized");
$title="Login Instructions";
echo "
You are not authorised to enter the site
";
exit;
}}
?>