An SQL injection attack is when a user injects SQL commands in to an unprotected SQL query.  This can lead to a number of issues, including modifying rows you didn't intend for the user to modify, dropped tables, deleted rows, and access to possibly sensitive data.  <b>It is critical that you learn and understand how these attacks work.  SQL injection attacks are arguably the most common way PHP websites get exploited.  The importance can not be overstated.</b>
 
An SQL injection attack is when a user injects SQL commands in to an unprotected SQL query.  This can lead to a number of issues, including modifying rows you didn't intend for the user to modify, dropped tables, deleted rows, and access to possibly sensitive data.  <b>It is critical that you learn and understand how these attacks work.  SQL injection attacks are arguably the most common way PHP websites get exploited.  The importance can not be overstated.</b>
   Exception encountered, of type "Error"
[3cc0ab70] /index.php?title=Validation&diff=450&oldid=449 Error from line 434 of /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DairikiDiff.php: Call to undefined function each()
Backtrace:
#0 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DairikiDiff.php(544): DiffEngine->diag(integer, integer, integer, integer, integer)
#1 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DairikiDiff.php(344): DiffEngine->compareSeq(integer, integer, integer, integer)
#2 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DairikiDiff.php(227): DiffEngine->diffLocal(array, array)
#3 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DairikiDiff.php(721): DiffEngine->diff(array, array)
#4 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DairikiDiff.php(859): Diff->__construct(array, array)
#5 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DairikiDiff.php(980): MappedDiff->__construct(array, array, array, array)
#6 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/TableDiffFormatter.php(194): WordLevelDiff->__construct(array, array)
#7 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DiffFormatter.php(140): TableDiffFormatter->changed(array, array)
#8 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DiffFormatter.php(82): DiffFormatter->block(integer, integer, integer, integer, array)
#9 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DifferenceEngine.php(888): DiffFormatter->format(Diff)
#10 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DifferenceEngine.php(802): DifferenceEngine->generateTextDiffBody(string, string)
#11 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DifferenceEngine.php(733): DifferenceEngine->generateContentDiffBody(WikitextContent, WikitextContent)
#12 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DifferenceEngine.php(662): DifferenceEngine->getDiffBody()
#13 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DifferenceEngine.php(632): DifferenceEngine->getDiff(string, string, string)
#14 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/diff/DifferenceEngine.php(453): DifferenceEngine->showDiff(string, string, string)
#15 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/page/Article.php(795): DifferenceEngine->showDiffPage(boolean)
#16 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/page/Article.php(506): Article->showDiffPage()
#17 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/actions/ViewAction.php(44): Article->view()
#18 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/MediaWiki.php(395): ViewAction->show()
#19 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/MediaWiki.php(273): MediaWiki->performAction(Article, Title)
#20 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/MediaWiki.php(566): MediaWiki->performRequest()
#21 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/includes/MediaWiki.php(414): MediaWiki->main()
#22 /misc/21/000/105/835/1/user/web/wiki.hashphp.org/index.php(41): MediaWiki->run()
#23 {main}