PHP and MySQL basic tutorial (2)_PHP tutorial

Data validation

Clear spaces

The trim function will clear the spaces at the beginning and end of the data. Its syntax is:

trim ($first_name);


Processing of required fields

In your database, some fields must be filled in. In this way, the corresponding fields corresponding to the HTML form are not allowed to be left blank. Of course, this verification process can be handled by client-side JavaScript scripts, but since we are talking about PHP, let’s use PHP for processing. The following code checks whether the user's last name is entered:

if (ereg(".", $first_name) == 1)

{

print (" Last name: " );

print ("$first_name");

$verify = "OK";

}

else

{

print ("< b> Error: < /b> Your last name has not been filled in");

$verify = "bad";

}

　 ereg pattern recognition function, used to determine whether the specified string contains a certain substring. Its first parameter is the substring to determine whether it is included, and the second parameter specifies the string to be searched, usually a variable. The Ereg function returns "0" (false) if the match fails, or "1" (true) if the match succeeds. Here the comma "." is a pattern wildcard, representing any character. In this way, the expression ereg(".", $first_name) == 1 means that the variable $first_name contains at least one character.

Check the e-mail address
Author: Yangmei compiled this article Number of clicks: 118

Use the following character constants as the first parameter of the ereg function, you can easily proceed The e-mail address was checked:

"@": Must contain @

"^@": Cannot start with @

"@.*..": In There must be characters between @ and .

"....*" : There must be at least two characters after .

" " : No spaces are allowed



Compare this With these parameter examples, you can also design some other input validations.

Check whether the username is unique

This action seems to be necessary: ​​

mysql_connect (localhost, username, password);



mysql_select_db (dbname);

$result = mysql_query ("SELECT * FROM tablename

WHERE USER_ID = '$USER_ID'

");

if ($row = mysql_fetch_array($result))

{

print ("< b> Error: < /b> username< b>");

print ("$USER_ID ");

print ("< /b> is already occupied, please choose another one and try again. ");

print ("< p>");

$verify = "bad";

}

else

{

print (" User ID: ");

print ("$USER_ID ");

}

　 The idea of ​​the code is very simple. After reading this, I believe it is already difficult I can’t hold you anymore.
Check if the username is unique
Author: Yangmei compiles this article Number of clicks: 118

　 This action seems to be necessary: ​​

mysql_connect (localhost, username, password) ;


mysql_select_db (dbname);

$result = mysql_query ("SELECT * FROM tablename

WHERE USER_ID = '$USER_ID'

");

if ($row = mysql_fetch_array($result))

{

print ("< b> Error: < /b> username< ; b>");

print ("$USER_ID ");

print ("< /b> is already occupied, please choose another one and try again. ");

print ("< p>");

$verify = "bad";

}

else

{

print (" User ID: ");

print ("$USER_ID ");

}

　The idea of ​​the code is very simple, read Here, I believe it can no longer trouble you.

http://www.bkjia.com/PHPjc/315117.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/315117.htmlTechArticleData validation cleans spaces. The trim function will clear the spaces at the beginning and end of the data. Its syntax is: trim ($first_name) ; Processing of required fields In your database, some fields must be filled in. ...