PHP and database connection_PHP tutorial

4. Database connection
With PHP you can easily connect to the database, request data and display it on your web site, and even modify data in the database. MySQL is a very popular database, and there are many tutorials on PHP and MySQL on the Internet. MySQL is free, which may attract many people. Due to its wide application, I don't want to go into details about the use of MySQL here. Oracle is widely used in enterprise applications, so we will use Oracle to introduce the connection between PHP and database. We will certainly not mention the design principles of the Oracle database, as this is beyond the scope of our discussion.
PHP provides two sets of functions to connect to Oracle, namely ORA_ and OCI functions. The ORA_ function is slightly outdated. The OCI function update is said to be better. The usage syntax of the two is almost the same. As mentioned before, your PHP installation options should support the use of both.
For more information on installing an Apache server with PHP3 support on Microsoft Windows platforms and more knowledge on Oracle databases, please consult the following URL: www.csoft.net/~vsbabu/articles/oraphp.html.

4.1 Connection

if (＄conn=Ora_Logon("user@TNSNAME","password"))
{
echo "SUCCESS ! Connected to database ";
}
else
{
echo "Failed :-( Could not connect to database ";
}
Ora_Logoff(＄conn);
phpinfo();
?>
The above code connects to the database using the Oracle database name, username and password defined by TNSNAME (specified in your tnsnames.ora file). On the basis of a successful connection, the ora_logon function returns a non-zero connection ID and stores it in the variable $conn.

4.2 Query

Assuming that the connection to the database is ready, let's actually apply the query to the database. The following code demonstrates a typical example of connecting and querying:
/*
* Connect to the database and execute queries
*/
function printoraerr(＄in_cur)
{
// Check if Oracle has an error
// If there is an error, display
// When the pointer is activated, this function is called after each request to Oracle
if(ora_errorcode(＄in_cur))
echo "Oracle code - ".ora_error(＄in_cur)." ";
return;
}
/**main program*/
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
";
?>
(Translator's Note: The above code segment lacks comments, please refer to the Oracle database function section of the PHP Manual)

4.3 Display results

The following code demonstrates how to query the database and output the results:
function printoraerr(＄in_cur, ＄conn)
{
// Check if Oracle has an error
// If there is an error, display
// When the pointer is activated, this function is called after each request to Oracle
// If it encounters 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 " ";
}
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 " ";
else
echo " ";
printoraerr(＄cursor,＄conn);
}
＄numrows ;
echo " ";
}
if (＄numrows==0)
echo " ";
else
{
echo " ";
echo " ";
echo " ";
echo " ";
}
echo "

".ora_columnname(＄cursor,＄i)."
".<br> ora_getcolumn(＄cursor,＄i)."	".ora_getcolumn(＄cursor,＄i)."
Query returned no records
Count	＄numrows

";
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"

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