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- PHP prepared statement with LIKE operator
- When using PHP preprocessing statements combined with LIKE for fuzzy queries, you need to pay attention to the parameter binding method and wildcard use. 1. You cannot directly write %'?%' in SQL because the question mark will be regarded as part of the string. The correct way is to pass % and search terms as parameters together or splice them on the PHP side before passing them in; 2. Multiple LIKE conditions can construct wildcard strings and bind parameters in turn, such as the fuzzy match between $searchName and $searchEmail corresponding to name and email; 3. Pay attention to the impact of input filtering, case sensitivity issues and full fuzzy query on performance to ensure that the code is safe and efficient.
- PHP Tutorial . Backend Development 904 2025-07-11 01:52:11
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- PHP convert string to integer
- There are three main methods for converting strings into integers in PHP: ① Use (int) type conversion, which is suitable for simple decimal conversion; ② Use the intval() function to support specified binary conversion; ③ Use filter_var() for secure verification conversion, which is suitable for processing external input. It is important to note that when the string format is not legal, it will return 0 or fail silently, so filter_var() should be used first in critical scenarios to avoid potential errors.
- PHP Tutorial . Backend Development 297 2025-07-11 01:44:50
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- PHP htmlspecialchars to prevent XSS
- XSS is a cross-site scripting attack that steals cookies or hijacks the session by inserting malicious scripts; htmlspecialchars() can escape special characters into HTML entities to prevent the browser from executing. 1.XSS often occurs when user input is directly displayed, such as comments, search boxes, etc.; 2.htmlspecialchars() avoids execution by escaping characters such as, &, etc.; 3. Correct use includes: always escape the output content, specify the encoding as UTF-8, not escape data before storage, and select processing methods according to the context; 4. Easily ignored points include: quotation marks are required to be closed in HTML attributes, rich text needs to be used with whitelist filters, and json_e should be used in JavaScript.
- PHP Tutorial . Backend Development 468 2025-07-11 01:27:51
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- How to replace only the first occurrence of a string in PHP
- The first match of replacing a string in PHP can be achieved by preg_replace or manual operation. When using preg_replace, you can control only the first match by setting the fourth parameter to 1. If you replace a normal string, you need to escape with preg_quote; for example, preg_replace('/apple/','orange',$string,1). If you do not use regular expressions, you can manually find the location where the target string first appears, split the string and replace it and splice it. As shown in the function replace_first, use strpos to locate and substr_replace to replace the specified part. Notes include
- PHP Tutorial . Backend Development 609 2025-07-11 01:09:30
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- Describe the difference between `include`, `require`, `include_once`, and `require_once` in php.
- In PHP, the main differences between include, require and their \_once versions are in the error handling method and whether the file is loaded repeatedly. 1. Include issues a warning when the file cannot be found but the script continues to be executed; 2. require throws a fatal error and terminates the script; 3. include\_once and require\_once respectively ensure that the file is loaded only once during the entire script life cycle to avoid repeated definition errors; 4. The selection basis is whether the file must exist and whether it is possible to be repeatedly introduced.
- PHP Tutorial . Backend Development 156 2025-07-11 00:53:51
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- What are PHP prepared statements
- PHP preprocessing statements safely execute queries by separating SQL logic from data. 1. Use placeholders (such as ? or :name) instead of directly embedding user input; 2. bind values ??and then execute to ensure that the input is correctly escaped to prevent SQL injection; 3. Improve performance when executing similar queries multiple times; 4. Make the code clearer and easier to maintain; 5. Common errors include directly splicing user input into SQL, ignoring error handling, and replacing representative names or column names with placeholders.
- PHP Tutorial . Backend Development 990 2025-07-11 00:45:11
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- php get current time in specific timezone
- To get the current time of the specified time zone, it is recommended to use the DateTime class to cooperate with DateTimeZone. The steps are: 1. Create a DateTimeZone object; 2. Create a DateTime object with the current time and bind the time zone; 3. Format the output time. Common time zones include Asia/Shanghai, Europe/London, etc. You can view the full list through DateTimeZone::listIdentifiers(). If you are used to procedural writing, you can use date_default_timezone_set() to set the default time zone and call date() to output the time, but this method will affect the global time settings. Notice
- PHP Tutorial . Backend Development 600 2025-07-11 00:39:51
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- PHP prepared statement dynamic query
- The following steps are required to construct a query dynamically using PHP preprocessing statements: 1. Collect WHERE conditions and parameters through an array, and flexibly construct the query statement based on the actual passed parameters; 2. Keep the WHERE clause dynamically changing when splicing SQL, and prepare the parameters uniformly; 3. When the number of parameters is greater than 0, call bind_param for binding, pay attention to the same order of the type string and the parameter; 4. Always use parameterized queries to prevent injection, field names or table names need to be whitelisted to verify, and LIKE and NULL values ??should also be handled specially to ensure security and accuracy.
- PHP Tutorial . Backend Development 867 2025-07-11 00:34:02
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- PHP header location not working after form submit
- Headerlocation jump failure is usually caused by the output being triggered in advance or the logic is not executed to the jump. 1. Make sure there is no output before the header, including spaces, BOM characters and echo/print statements; 2. Check whether the form method and action are correct, and confirm that the logical branch is executed to the jump position; 3. Add exit/die to the header and terminate the subsequent code; 4. Use JS jump temporarily to replace but not recommended solution if necessary. Solve the output, logic and termination statements in order.
- PHP Tutorial . Backend Development 270 2025-07-11 00:33:11
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- PHP header location whitespace before php tag
- The reason and solution for jumping does not take effect or prompting "headersalreadysent" error: 1. The whitespace character at the beginning of the file causes the header to fail, check and delete
- PHP Tutorial . Backend Development 721 2025-07-11 00:31:11
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- PHP sprintf format examples
- The sprintf() function in PHP is used to format strings and return results. 1. Format numbers to be formatted as fixed decimal places, you can use %.2f, %.1f and other formats to automatically round; 2. Complement and width control can be implemented through d or M, indicating complementary or fill spaces respectively; 3. String truncation and splicing use %.10s or .10s to limit length and alignment; 4. When using multiple parameters in a mixed manner, %s, %d, and %f correspond to strings, integers, and floating-point numbers, respectively, and the order must be consistent. This function is very practical in generating logs, reports and other scenarios, making the code more neat and controllable.
- PHP Tutorial . Backend Development 803 2025-07-11 00:27:21
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- PHP session not working on mobile or in some browsers
- PHP session fails on mobile phones or some browsers, mainly due to cookie settings, session ID delivery or cross-domain issues. 1. The SessionID is not saved or passed correctly. If the third-party cookies are disabled, the user disables the cookies or misses the sid, make sure to call session_start() and check the cookie settings. 2. Mobile browser policies are strict. For example, iOSSafari blocks third-party cookies in iframes. Iframes should avoid nesting key processes and unifying domain names. 3. The Session file is not read and written correctly. If the permissions are insufficient or multiple servers are not synchronized, you need to check the log and debug output to confirm consistency. 4. HTTPS
- PHP Tutorial . Backend Development 849 2025-07-11 00:20:21
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- How to use prepared statements with mysqli
- PreparedstatementsinMySQLipreventSQLinjectionandimproveefficiencybyseparatingSQLlogicfromdatainputs.Tousethemeffectively:1)connecttothedatabase,2)preparetheSQLstatementwithplaceholders,3)bindparameterscorrectlybytype(sforstring,iforinteger,etc.),4)ex
- PHP Tutorial . Backend Development 839 2025-07-11 00:17:50
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- How to debug a PHP function?
- The key to debugging PHP functions is to master practical methods and tools. 1. First check whether the input parameters are correct, use var_dump or print_r to print parameter values, and confirm whether the type, format and default values ??are reasonable; 2. Turn on error reports (error_reporting and display_errors), display all error messages, and help position variables undefined and keys, etc.; 3. Segmented testing logic, and determine whether the code execution process and intermediate results are in line with expectations through temporary output or logging; 4. Use debugging tools such as Xdebug to cooperate with IDE to achieve breakpoint debugging, single-step execution, etc. to improve efficiency; 5. Maintain good code specifications to reduce naming confusion or unclear function responsibilities
- PHP Tutorial . Backend Development 289 2025-07-10 13:58:01
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