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There is a question about the sql left join. Why are all nulls found instead of no data? domain is the domain name table, domain_sell is the listed domain name table, domain_auction_history is the domain name auction table. This is my query statement: SELECT d.,s.,MAX(h.price) AS max_price FROM domain d LEFT JOIN domain_sell s USING(domain_id) LEFT JOIN domain_auction_history h USING(domain_id) WHERE d.status IN('Already on the shelves', 'Under Auction')
1. There is a question about the sql left connection, why are all null found, and No data?
Introduction: domain is the domain name table, domain_sell is the listed domain name table, domain_auction_history is the domain name auction table. This is my query statement: SELECT d.,s.,MAX(h.price) AS max_price FROM domain d LEFT JOIN domain_sell s USING(domain_id) LEFT JO...
2. Friendly links Check the code for php to implement home page link query and friendly link check
Introduction: Friendly link check: Friendly link check PHP implements the code for home page link query and friendly link check: Copy the code and the code is as follows ; ="check"){ $domain=$_POST['domain']; //If the domain name form item is empty, get the address bar parameters if($domain==""){ $domain=$_GET
3. Object Model PHP 50 Object Model Deep Exploration of Static Members like
Introduction: Object Model: Object Model PHP 50 Object Static members like model deep exploration: Static properties contain data to be encapsulated in a class and can be shared by all instances of the class. In fact, in addition to belonging to a fixed class and restricting access methods, the static properties of a class are very similar to the global variables of a function. We use a static property Counter::$count in the following example. It belongs to the Counter class and not to any instance of Counter. You cannot use this to refer to it, but you can use self or other valid naming expressions. In the example, the getCount method returns self::$count instead of
4. Phased summary of project research Phased summary of good php code style
Introduction: Phased summary of project research: Phased summary of project research Phased summary of good PHP code style: This article summarizes the style of PHP good code and shares it with everyone for your reference. The details are as follows : 1. Avoid using the magic number if($age<18){}. I don’t quite understand why this 18 is like this. You can define 28 in a variable. The name of this variable indicates the meaning of this value. $adult_age = 18; //The cut-off point age of adulthood if ($age<$adult_age){} 2. The return result of the function: Do not use a Variables to store the return result Once you know the return result, you should return it immediately. This is good
5. PHP file upload performance - multiple file upload
##Introduction: PHP file upload function - multi-file upload This section mainly introduces the multi-file upload function of PHP upload files. As long as the file upload tag in the form is named in the form of an array, multiple files can be uploaded simultaneously. Let's take a look at an example:--------------------------------------------- --------------------------