PHParrayshandledatacollectionsefficientlyusingindexedorassociativestructures;theyarecreatedwitharray()or[],accessedviakeys,modifiedbyassignment,iteratedwithforeach,andmanipulatedusingfunctionslikecount(),in_array(),array_key_exists(),array_push(),arr

TheObserverdesignpatternenablesautomaticnotificationofdependentobjectswhenasubject'sstatechanges.1)Itdefinesaone-to-manydependencybetweenobjects;2)Thesubjectmaintainsalistofobserversandnotifiesthemviaacommoninterface;3)Observersimplementanupdatemetho

$_COOKIEisaPHPsuperglobalforaccessingcookiessentbythebrowser;cookiesaresetusingsetcookie()beforeoutput,readvia$_COOKIE['name'],updatedbyresendingwithnewvalues,anddeletedbysettinganexpiredtimestamp,withsecuritybestpracticesincludinghttponly,secureflag

Useinterfacestodefinecontractsforunrelatedclasses,ensuringtheyimplementspecificmethods;2.Useabstractclassestosharecommonlogicamongrelatedclasseswhileenforcinginheritance;3.Usetraitstoreuseutilitycodeacrossunrelatedclasseswithoutinheritance,promotingD

B-TreeindexesarebestformostPHPapplications,astheysupportequalityandrangequeries,sorting,andareidealforcolumnsusedinWHERE,JOIN,orORDERBYclauses;2.Full-Textindexesshouldbeusedfornaturallanguageorbooleansearchesontextfieldslikearticlesorproductdescripti

Public members can be accessed at will; 2. Private members can only be accessed within the class; 3. Protected members can be accessed in classes and subclasses; 4. Rational use can improve code security and maintainability.

Using MySQLi object-oriented method: establish a connection, preprocess UPDATE statements, bind parameters, execute and check the results, and finally close the resource. 2. Using MySQLi procedure method: connect to the database through functions, prepare statements, bind parameters, perform updates, and close the connection after processing errors. 3. Use PDO: Connect to the database through PDO, set exception mode, pre-process SQL, bind parameters, perform updates, use try-catch to handle exceptions, and finally release resources. Always use preprocessing statements to prevent SQL injection, verify user input, and close connections in time.

Usedate('Y-m-dH:i:s')withdate_default_timezone_set()togetcurrentdateandtimeinPHP,ensuringaccurateresultsbysettingthedesiredtimezonelike'America/New_York'beforecallingdate().