


Some issues that need to be paid attention to when operating MySQL database in PHP (translated) Some issues are very well said. . Quite novel. . -Database related_PHP tutorial
Some issues to pay attention to when operating MySQL database in PHP
1. Semicolon exceptions
For MySQL, the first thing you must remember is that each line of commands ends with a semicolon (;) , but... there is no absolute thing, and it is the same here. When a line of MySQL is inserted into the PHP code, it is best to omit the following semicolon, for example:
mysql_query ("INSERT INTO tablename (first_name, last_name)
VALUES ('$first_name', '$last_name')
");
This is because PHP also ends a line with a semicolon, and extra semicolons sometimes make PHP's syntax The parser doesn't understand it, so it's better to omit it. In this case, although the semicolon is omitted, PHP will automatically add it for you when executing the MySQL command.
There is another situation where you don’t need to add a semicolon. When you want to display the vertical arrangement of the fields you want instead of the usual horizontal arrangement, you can use G to end a line of SQL statements. In this case, there is no need for a semicolon, for example:
SELECT * FROM PENPALS WHERE USER_ID = 1G
2. TEXT, DATE, and SET data types
The fields of the MySQL data table must have a data type defined. There are about 25 options, most of which are straightforward and require no further explanation. But there are a few that need to be mentioned.
TEXT is not a data type, although some books may say so. It should actually be "LONG VARCHAR" or "MEDIUMTEXT".
The format of DATE data type is YYYY-MM-DD, for example: 1999-12-08. You can easily use the date function to get the current system time in this format:
date("Y-m-d")
Moreover, you can subtract between DATA data types to get the difference in days:
$age = ($current_date - $birthdate);
Set SET is a useful data type. It is somewhat similar to enumeration ENUM, except that SET can save multiple values and ENUM can only save one value. Moreover, the SET type can only have a maximum of 64 predefined values, while the ENUM type can handle a maximum of 65,535 predefined values. And what if we need a collection with more than 64 values? At this time, you need to define multiple collections to solve this problem together.
3. Wildcard

What’s still popular is the ease of use, flexibility and a strong ecosystem. 1) Ease of use and simple syntax make it the first choice for beginners. 2) Closely integrated with web development, excellent interaction with HTTP requests and database. 3) The huge ecosystem provides a wealth of tools and libraries. 4) Active community and open source nature adapts them to new needs and technology trends.

PHP and Python are both high-level programming languages that are widely used in web development, data processing and automation tasks. 1.PHP is often used to build dynamic websites and content management systems, while Python is often used to build web frameworks and data science. 2.PHP uses echo to output content, Python uses print. 3. Both support object-oriented programming, but the syntax and keywords are different. 4. PHP supports weak type conversion, while Python is more stringent. 5. PHP performance optimization includes using OPcache and asynchronous programming, while Python uses cProfile and asynchronous programming.

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP remains important in the modernization process because it supports a large number of websites and applications and adapts to development needs through frameworks. 1.PHP7 improves performance and introduces new features. 2. Modern frameworks such as Laravel, Symfony and CodeIgniter simplify development and improve code quality. 3. Performance optimization and best practices further improve application efficiency.

PHPhassignificantlyimpactedwebdevelopmentandextendsbeyondit.1)ItpowersmajorplatformslikeWordPressandexcelsindatabaseinteractions.2)PHP'sadaptabilityallowsittoscaleforlargeapplicationsusingframeworkslikeLaravel.3)Beyondweb,PHPisusedincommand-linescrip

PHP type prompts to improve code quality and readability. 1) Scalar type tips: Since PHP7.0, basic data types are allowed to be specified in function parameters, such as int, float, etc. 2) Return type prompt: Ensure the consistency of the function return value type. 3) Union type prompt: Since PHP8.0, multiple types are allowed to be specified in function parameters or return values. 4) Nullable type prompt: Allows to include null values and handle functions that may return null values.


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