Basic operation methods of PHP on text database_PHP tutorial

php(做为现在的主流开发语言)实现对文本数据库的数据显示、加入、修改、删除、查询五大基本操作的方法
我用一个留言本程序作为例子，阐述php(做为现在的主流开发语言)实现对文本数据库的数据显示、加入、修改、删除、查询五大基本操作的方法。
此文本数据库共有字段10个：客户IP、发言时间、客户名、客户EMAIL、客户主页地址、留言表情图片名、客户QQ、客户形象图片、留言内容、管理员回复内容。

1、加入数据程序段。

$date=date("Y-m-d H:i:s");//取得系统时间
$ip = $HTTP_SERVER_VARS[REMOTE_ADDR]; //取得发言的IP地址
$text=encode($gb_text);//去掉留言内容后面的空格.
$fp=fopen("gb.dat","a");//以只写模式打开gb.dat文本文件,文件指针指向文件尾部.
$str=$ip."　".$date."　".$gb_name."　".$gb_email."　".$gb_home."　".$face."　".$gb_qq."　".$head."　".$text."　".$reply." ";//将所有留言的数据赋予变量$str，"　"的目的是用来今后作数据分割时的数据间隔符号。
fwrite($fp,$str);//将数据写入文件
fclose($fp);//关闭文件
showmessage("留言成功!","index.php(做为现在的主流开发语言)","3");//留言成功，3秒后自动返回主界面。
其中的$gb_name 、$gb_email、$gb_home、$face、$gb_qq、$head、$gb_text、$reply是由发言表单传过来的数据。

2、数据显示程序段

＜?
if (file_exists("gb.dat")){//Check whether the file exists
$array=file("gb.dat");//Read the entire content of the file into Array $array
$arr=array_reverse($array);//Reverse the data in $array (that is, the last row is the first row, and so on) and read into each unit of array $arr ($ arr[0]...).
$num=count($array);//Get the number of information in the array $array (one line per line)
if ($num>0){//If the number of information is greater than zero (i.e. text database Not empty)
$total=ceil($num/$pagesize);//Calculate the total number of pages (take the largest integer, that is, round up any decimal point, $pagesize is the default value displayed on each page Number of information)
if($page＜1){//If the current page number is less than 1
$page=1;//Assign the value to 1
}
$number=($page -1)*$pagesize;//Calculate the digital number of the first message currently displayed (the digital number starts from zero, mainly to achieve the purpose of corresponding to the array unit number)
for($i=0;$i ＜=$pagesize-1;$i++){//Enter the loop
$row=explode("　",$arr[$number]);//Use "　" as the separator to divide each number in the array $arr $number units of data, and assign these data to the array $rom
list($ip,$datetime,$name,$email,$home,$face,$qq,$head,$text,$reply) =$row;//Assign the unit data in the array $row to the variables in the brackets in order
?＞
＜img src=＜? echo $head ?＞＞//Display the customer image picture
＜br＞
＜font color="#0099CC"＞Nickname【＜? echo $name ?＞＜font size="2"＞】＜br＞//Display customer name
Published on: ＜? echo $datetime ?＞//Display the message publishing time
＜br＞
＜img src=＜? echo $face ?＞＞//Display the customer message emoticon picture
＜? echo $name ?＞ said: ＜? echo $text; ?＞//Display customer message content
＜br＞
＜? echo $reply ?＞//Display reply content
＜br＞
＜a href="＜ ? echo $home ?＞" target="_blank"＞Visit the homepage of ＜? echo $name ?＞＜/a＞//Hyperlink to the customer homepage
＜a href="mailto:＜? echo $email ? ＞"＞Send an email to ＜? echo $name ?＞＜/a＞//The connection of the customer’s E-MAIL
＜? echo $name ?＞’s QQ number is ＜? echo $qq ?＞//Display the customer The IP address of the QQ number
＜? echo $name ?＞ is ＜? echo $ip ?＞" //Display the customer’s IP address
＜a href="reply.php(as now mainstream development language)?time=＜? echo $datetime ?＞"＞Reply＜/a＞//Connection statement for message reply
＜a href="del.php(as now mainstream development language) ?time=＜? echo $datetime ?＞"＞Delete＜/a＞//The statement for message deletion (use the customer message time $datetime as the deletion identifier) ​​
＜br＞
＜?
if ($number == $num-1)//If the unit number of the array is equal to the total number of messages minus one (because the unit number starts with zero, this means this is the last message)
{
break;//Jump out of the loop
}
$number = $number + 1; //Add 1 to the array unit number
}//End of loop
}
if ($page ＜＞ 1)//If the current page number is not equal to 1
{
$back = $page - 1;//Decrease the current page number by 1, and assign this value to the variable $back
echo "＜a href=index.php(as the current mainstream development language)?page=1＞First page＜/a＞";//Display the link to the first page
echo "＜a href=index.php(as the current mainstream development language)?page=$back＞Previous page＜/a＞"; The current page number is equal to $back, and Display its connection
}
if ($page ＜＞ $total)//If the current page number is not equal to the total page number (the last page number)
{
$next = $ page + 1;//Add 1 to the current page number and assign it to the variable $next
echo " ＜a href=index.php(as the current mainstream development language)?page=$next＞ Next page＜/a＞";//Show the next page link
echo "＜a href=index.php(as the current mainstream development language)?page=$total＞Finally One page＜/a＞"; Display the last page link
}
echo "Number of pages: $page / $total";//Display the current page number and display the last page number
echo "There are $num messages in total";//Display message number information
}
else {
echo "