\n <?php\n \/\/ isset(xx) 測試xx是否設置了\n if(isset($_SESSION['user_account'])){\n echo '你好，' . $_SESSION['user_account'];\n }\n else{\n echo '游客';\n }\n \/\/$conn->close();\n ?>\n <\/p>\n
Rendering: <\/p>\n
<\/p>\n
The above is the entire content of this article. I hope it will be helpful to everyone in learning PHP programming. <\/p>\n
Go straight to the topic, first look at the code for php to verify whether the login name and password are correct:
<?php $servername = "服務器名"; $username = "賬戶名"; $password = "密碼"; $dbname = "數據庫名"; ?> <?php // Session需要先啟動。 session_start(); //判斷uname和pwd是否賦值 if(isset($_POST['uname']) && isset($_POST['pwd'])){ $name = $_POST['uname']; $pwd = $_POST['pwd']; //連接數據庫 $conn = new mysqli($servername, $username, $password, $dbname); if ($conn->connect_error) { die("Connection failed: " . $conn->connect_error); } //驗證內容是否與數據庫的記錄吻合。 $sql = "SELECT * FROM test_students_all WHERE (student_name='$name') AND (password='$pwd')"; //執(zhí)行上面的sql語句并將結果集賦給result。 $result = $conn->query($sql); //判斷結果集的記錄數是否大于0 if ($result->num_rows > 0) { $_SESSION['user_account'] = $name; // 輸出每行數據 while($row = $result->fetch_assoc()) { echo '<p>' . $row['student_nbr'] . '<br/>' . $row['student_name'] . '(' . $row['sex'] . ')' . '<br/>' . $row['class'] . '<br/>' . $row['major'].'</p>'; // <p><img src="student_images/CLASS/STUDENT_NBR.jpg" /></p> echo '<p><img src="student_images/' . $row['class'] . '/' . $row['student_nbr'] . '.jpg" /></p>'; } } else { echo "沒有您要的信息"; } $conn->close(); } ?> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>登錄校驗</title> </head> <body> <p> <?php // isset(xx) 測試xx是否設置了 if(isset($_SESSION['user_account'])){ echo '你好，' . $_SESSION['user_account']; } else{ echo '游客'; } //$conn->close(); ?> </p> <form method="POST"> <input type="text" name="uname" placeholder="用戶名" /> <br /> <input type="password" name="pwd" placeholder="密碼" /> <br /> <input type="submit"> </form> </body> </html>
Rendering:
The above is the entire content of this article. I hope it will be helpful to everyone in learning PHP programming.
Undress images for free
AI-powered app for creating realistic nude photos
Online AI tool for removing clothes from photos.
AI clothes remover
Swap faces in any video effortlessly with our completely free AI face swap tool!
Easy-to-use and free code editor
Chinese version, very easy to use
Powerful PHP integrated development environment
Visual web development tools
God-level code editing software (SublimeText3)
exit() is a function in PHP that is used to terminate script execution immediately. Common uses include: 1. Terminate the script in advance when an exception is detected, such as the file does not exist or verification fails; 2. Output intermediate results during debugging and stop execution; 3. Call exit() after redirecting in conjunction with header() to prevent subsequent code execution; In addition, exit() can accept string parameters as output content or integers as status code, and its alias is die().
The rational use of semantic tags in HTML can improve page structure clarity, accessibility and SEO effects. 1. Used for independent content blocks, such as blog posts or comments, it must be self-contained; 2. Used for classification related content, usually including titles, and is suitable for different modules of the page; 3. Used for auxiliary information related to the main content but not core, such as sidebar recommendations or author profiles. In actual development, labels should be combined and other, avoid excessive nesting, keep the structure simple, and verify the rationality of the structure through developer tools.
To reset the root password of MySQL, please follow the following steps: 1. Stop the MySQL server, use sudosystemctlstopmysql or sudosystemctlstopmysqld; 2. Start MySQL in --skip-grant-tables mode, execute sudomysqld-skip-grant-tables&; 3. Log in to MySQL and execute the corresponding SQL command to modify the password according to the version, such as FLUSHPRIVILEGES;ALTERUSER'root'@'localhost'IDENTIFIEDBY'your_new
When handling NULL values ??in MySQL, please note: 1. When designing the table, the key fields are set to NOTNULL, and optional fields are allowed NULL; 2. ISNULL or ISNOTNULL must be used with = or !=; 3. IFNULL or COALESCE functions can be used to replace the display default values; 4. Be cautious when using NULL values ??directly when inserting or updating, and pay attention to the data source and ORM framework processing methods. NULL represents an unknown value and does not equal any value, including itself. Therefore, be careful when querying, counting, and connecting tables to avoid missing data or logical errors. Rational use of functions and constraints can effectively reduce interference caused by NULL.
Turn on MySQL slow query logs and analyze locationable performance issues. 1. Edit the configuration file or dynamically set slow_query_log and long_query_time; 2. The log contains key fields such as Query_time, Lock_time, Rows_examined to assist in judging efficiency bottlenecks; 3. Use mysqldumpslow or pt-query-digest tools to efficiently analyze logs; 4. Optimization suggestions include adding indexes, avoiding SELECT*, splitting complex queries, etc. For example, adding an index to user_id can significantly reduce the number of scanned rows and improve query efficiency.
mysqldump is a common tool for performing logical backups of MySQL databases. It generates SQL files containing CREATE and INSERT statements to rebuild the database. 1. It does not back up the original file, but converts the database structure and content into portable SQL commands; 2. It is suitable for small databases or selective recovery, and is not suitable for fast recovery of TB-level data; 3. Common options include --single-transaction, --databases, --all-databases, --routines, etc.; 4. Use mysql command to import during recovery, and can turn off foreign key checks to improve speed; 5. It is recommended to test backup regularly, use compression, and automatic adjustment.
MySQL paging is commonly implemented using LIMIT and OFFSET, but its performance is poor under large data volume. 1. LIMIT controls the number of each page, OFFSET controls the starting position, and the syntax is LIMITNOFFSETM; 2. Performance problems are caused by excessive records and discarding OFFSET scans, resulting in low efficiency; 3. Optimization suggestions include using cursor paging, index acceleration, and lazy loading; 4. Cursor paging locates the starting point of the next page through the unique value of the last record of the previous page, avoiding OFFSET, which is suitable for "next page" operation, and is not suitable for random jumps.
TosecurelyconnecttoaremoteMySQLserver,useSSHtunneling,configureMySQLforremoteaccess,setfirewallrules,andconsiderSSLencryption.First,establishanSSHtunnelwithssh-L3307:localhost:3306user@remote-server-Nandconnectviamysql-h127.0.0.1-P3307.Second,editMyS