if (!$mask) { file_put_contents($pathname, $message . "\n", FILE_APPEND);
file_put_contents - [internal], line ??
Cake\Log\Engine\FileLog::log() - CORE/src/Log/Engine/FileLog.php, line 140
Cake\Log\Log::write() - CORE/src/Log/Log.php, line 392
Cake\Log\Log::warning() - CORE/src/Log/Log.php, line 477
DebugKit\ToolbarService::isSuspiciouslyProduction() - ROOT/vendor/cakephp/debug_kit/src/ToolbarService.php, line 169
DebugKit\ToolbarService::isEnabled() - ROOT/vendor/cakephp/debug_kit/src/ToolbarService.php, line 105
DebugKit\Plugin::bootstrap() - ROOT/vendor/cakephp/debug_kit/src/Plugin.php, line 48
Cake\Http\BaseApplication::pluginBootstrap() - CORE/src/Http/BaseApplication.php, line 182
Cake\Http\Server::bootstrap() - CORE/src/Http/Server.php, line 111
Cake\Http\Server::run() - CORE/src/Http/Server.php, line 79
[main] - ROOT/webroot/index.php, line 40
Notice: file_put_contents() [function.file-put-contents]: Write of 1108 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Notice (8): SplFileObject::fwrite() [<a href='https://secure.php.net/splfileobject.fwrite'>splfileobject.fwrite</a>]: Write of 5437 bytes failed with errno=28 No space left on device [CORE/src/Cache/Engine/FileEngine.php, line 141]
SplFileObject::fwrite() - [internal], line ??
Cake\Cache\Engine\FileEngine::set() - CORE/src/Cache/Engine/FileEngine.php, line 141
Cake\Database\Schema\CachedCollection::describe() - CORE/src/Database/Schema/CachedCollection.php, line 85
Cake\ORM\Table::getSchema() - CORE/src/ORM/Table.php, line 513
Cake\ORM\Query::addDefaultTypes() - CORE/src/ORM/Query.php, line 290
Cake\ORM\Query::__construct() - CORE/src/ORM/Query.php, line 184
Cake\ORM\Table::query() - CORE/src/ORM/Table.php, line 1702
Cake\ORM\Table::find() - CORE/src/ORM/Table.php, line 1263
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6426
App\Controller\NewsController::get_data() - APP/Controller/NewsController.php, line 5701
App\Controller\NewsController::action_cache() - APP/Controller/NewsController.php, line 5625
App\Controller\NewsController::cache_action() - APP/Controller/NewsController.php, line 5281
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3436
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Notice: file_put_contents() [function.file-put-contents]: Write of 3152 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Notice (8): unserialize() [<a href='https://secure.php.net/function.unserialize'>function.unserialize</a>]: Error at offset 4079 of 4085 bytes [APP/Controller/NewsController.php, line 5571]
unserialize - [internal], line ??
App\Controller\NewsController::action_cache() - APP/Controller/NewsController.php, line 5571
App\Controller\NewsController::cache_action() - APP/Controller/NewsController.php, line 5281
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6481
App\Controller\NewsController::get_data() - APP/Controller/NewsController.php, line 5701
App\Controller\NewsController::action_cache() - APP/Controller/NewsController.php, line 5625
App\Controller\NewsController::cache_action() - APP/Controller/NewsController.php, line 5281
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3436
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Notice: file_put_contents() [function.file-put-contents]: Write of 2758 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Notice (8): SplFileObject::fwrite() [<a href='https://secure.php.net/splfileobject.fwrite'>splfileobject.fwrite</a>]: Write of 822 bytes failed with errno=28 No space left on device [CORE/src/Cache/Engine/FileEngine.php, line 141]
SplFileObject::fwrite() - [internal], line ??
Cake\Cache\Engine\FileEngine::set() - CORE/src/Cache/Engine/FileEngine.php, line 141
Cake\Database\Schema\CachedCollection::describe() - CORE/src/Database/Schema/CachedCollection.php, line 85
Cake\ORM\Table::getSchema() - CORE/src/ORM/Table.php, line 513
Cake\ORM\Query::addDefaultTypes() - CORE/src/ORM/Query.php, line 290
Cake\ORM\Query::__construct() - CORE/src/ORM/Query.php, line 184
Cake\ORM\Table::query() - CORE/src/ORM/Table.php, line 1702
Cake\ORM\Table::find() - CORE/src/ORM/Table.php, line 1263
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6539
App\Controller\NewsController::get_data() - APP/Controller/NewsController.php, line 5701
App\Controller\NewsController::action_cache() - APP/Controller/NewsController.php, line 5625
App\Controller\NewsController::cache_action() - APP/Controller/NewsController.php, line 5281
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3436
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Notice: file_put_contents() [function.file-put-contents]: Write of 3151 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Warning (2): Undefined array key "nsort" [APP/Controller/NewsController.php, line 3613]
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3613
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Http\Middleware\BodyParserMiddleware::process() - CORE/src/Http/Middleware/BodyParserMiddleware.php, line 157
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Routing\Middleware\RoutingMiddleware::process() - CORE/src/Routing/Middleware/RoutingMiddleware.php, line 161
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Routing\Middleware\AssetMiddleware::process() - CORE/src/Routing/Middleware/AssetMiddleware.php, line 77
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Error\Middleware\ErrorHandlerMiddleware::process() - CORE/src/Error/Middleware/ErrorHandlerMiddleware.php, line 126
Notice: file_put_contents() [function.file-put-contents]: Write of 2074 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Warning (2): Trying to access array offset on value of type null [APP/Controller/NewsController.php, line 3613]
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3613
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Http\Middleware\BodyParserMiddleware::process() - CORE/src/Http/Middleware/BodyParserMiddleware.php, line 157
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Routing\Middleware\RoutingMiddleware::process() - CORE/src/Routing/Middleware/RoutingMiddleware.php, line 161
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Routing\Middleware\AssetMiddleware::process() - CORE/src/Routing/Middleware/AssetMiddleware.php, line 77
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Error\Middleware\ErrorHandlerMiddleware::process() - CORE/src/Error/Middleware/ErrorHandlerMiddleware.php, line 126
Notice: file_put_contents() [function.file-put-contents]: Write of 2098 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Warning (2): Undefined array key "nsort" [APP/Controller/NewsController.php, line 3613]
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3613
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Http\Middleware\BodyParserMiddleware::process() - CORE/src/Http/Middleware/BodyParserMiddleware.php, line 157
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Routing\Middleware\RoutingMiddleware::process() - CORE/src/Routing/Middleware/RoutingMiddleware.php, line 161
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Routing\Middleware\AssetMiddleware::process() - CORE/src/Routing/Middleware/AssetMiddleware.php, line 77
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Error\Middleware\ErrorHandlerMiddleware::process() - CORE/src/Error/Middleware/ErrorHandlerMiddleware.php, line 126
Notice: file_put_contents() [function.file-put-contents]: Write of 2074 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Warning (2): Trying to access array offset on value of type null [APP/Controller/NewsController.php, line 3613]
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3613
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Http\Middleware\BodyParserMiddleware::process() - CORE/src/Http/Middleware/BodyParserMiddleware.php, line 157
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Routing\Middleware\RoutingMiddleware::process() - CORE/src/Routing/Middleware/RoutingMiddleware.php, line 161
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Routing\Middleware\AssetMiddleware::process() - CORE/src/Routing/Middleware/AssetMiddleware.php, line 77
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Error\Middleware\ErrorHandlerMiddleware::process() - CORE/src/Error/Middleware/ErrorHandlerMiddleware.php, line 126
Notice: file_put_contents() [function.file-put-contents]: Write of 2098 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140 SQL语句的各个关键字的解析过程详细总结 - 站长搜索
include - ROOT/plugins/Kuhuang/templates/Websites/view.php, line 430
Cake\View\View::_evaluate() - CORE/src/View/View.php, line 1184
Cake\View\View::_render() - CORE/src/View/View.php, line 1138
Cake\View\View::render() - CORE/src/View/View.php, line 769
Cake\Controller\Controller::render() - CORE/src/Controller/Controller.php, line 762
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3938
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Http\Middleware\BodyParserMiddleware::process() - CORE/src/Http/Middleware/BodyParserMiddleware.php, line 157
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Notice: file_put_contents() [function.file-put-contents]: Write of 2422 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Warning (2): Trying to access array offset on value of type null [ROOT/plugins/Kuhuang/templates/Websites/view.php, line 430]
include - ROOT/plugins/Kuhuang/templates/Websites/view.php, line 430
Cake\View\View::_evaluate() - CORE/src/View/View.php, line 1184
Cake\View\View::_render() - CORE/src/View/View.php, line 1138
Cake\View\View::render() - CORE/src/View/View.php, line 769
Cake\Controller\Controller::render() - CORE/src/Controller/Controller.php, line 762
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3938
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Http\Middleware\BodyParserMiddleware::process() - CORE/src/Http/Middleware/BodyParserMiddleware.php, line 157
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Notice: file_put_contents() [function.file-put-contents]: Write of 2446 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
">
Warning (2): Undefined array key "nsort" [ROOT/plugins/Kuhuang/templates/Websites/view.php, line 430]
include - ROOT/plugins/Kuhuang/templates/Websites/view.php, line 430
Cake\View\View::_evaluate() - CORE/src/View/View.php, line 1184
Cake\View\View::_render() - CORE/src/View/View.php, line 1138
Cake\View\View::render() - CORE/src/View/View.php, line 769
Cake\Controller\Controller::render() - CORE/src/Controller/Controller.php, line 762
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3938
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Http\Middleware\BodyParserMiddleware::process() - CORE/src/Http/Middleware/BodyParserMiddleware.php, line 157
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Notice: file_put_contents() [function.file-put-contents]: Write of 2422 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140
Warning (2): Trying to access array offset on value of type null [ROOT/plugins/Kuhuang/templates/Websites/view.php, line 430]
include - ROOT/plugins/Kuhuang/templates/Websites/view.php, line 430
Cake\View\View::_evaluate() - CORE/src/View/View.php, line 1184
Cake\View\View::_render() - CORE/src/View/View.php, line 1138
Cake\View\View::render() - CORE/src/View/View.php, line 769
Cake\Controller\Controller::render() - CORE/src/Controller/Controller.php, line 762
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3938
Cake\Controller\Controller::invokeAction() - CORE/src/Controller/Controller.php, line 539
Cake\Controller\ControllerFactory::handle() - CORE/src/Controller/ControllerFactory.php, line 140
Cake\Controller\ControllerFactory::invoke() - CORE/src/Controller/ControllerFactory.php, line 115
Cake\Http\BaseApplication::handle() - CORE/src/Http/BaseApplication.php, line 317
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 77
Cake\Http\Middleware\CsrfProtectionMiddleware::process() - CORE/src/Http/Middleware/CsrfProtectionMiddleware.php, line 164
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\I18n\Middleware\LocaleSelectorMiddleware::process() - CORE/src/I18n/Middleware/LocaleSelectorMiddleware.php, line 61
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Cake\Http\Middleware\BodyParserMiddleware::process() - CORE/src/Http/Middleware/BodyParserMiddleware.php, line 157
Cake\Http\Runner::handle() - CORE/src/Http/Runner.php, line 73
Notice: file_put_contents() [function.file-put-contents]: Write of 2446 bytes failed with errno=28 No space left on device in /www/wwwroot/www.adminso.com/vendor/cakephp/cakephp/src/Log/Engine/FileLog.php on line 140 2022-09-23 17:05:09转载来源: 网络整理/侵权必删
1. FROM FROM后面的表标识了这条语句要查询的数据源。和一些子句如,(1-J1)笛卡尔积,(1-J2)ON过滤,(1-J3)添加外部列,所要应用的对象。FROM过程之后会生成一个虚拟表VT1。 (1-J1)笛卡尔积 这个步骤会计算两个相关联表的笛卡尔积(CROSS JOIN) ,生成虚拟表VT1-J1。 (1-J2)ON过滤 这个步骤基于虚拟表VT1-J1这一个虚拟表进行过滤,过滤出所有满足ON 谓词条件的列,生成虚拟表VT1-J2。 (1-J3)添加外部行 如果使用了外连接,保留表中的不符合ON条件的列也会被加入到VT1-J2中,作为外部行,生成虚拟表VT1-J3。 2. WHERE 对VT1过程中生成的临时表进行过滤,满足where子句的列被插入到VT2表中。 3. GROUP BY 这个子句会把VT2中生成的表按照GROUP BY中的列进行分组。生成VT3表。 4. HAVING 这个子句对VT3表中的不同的组进行过滤,满足HAVING条件的子句被加入到VT4表中。 5. SELECT 这个子句对SELECT子句中的元素进行处理,生成VT5表。 (5-1)计算表达式 计算SELECT 子句中的表达式,生成VT5-1 (5-2)DISTINCT 寻找VT5-1中的重复列,并删掉,生成VT5-2 (5-3)TOP 从ORDER BY子句定义的结果中,筛选出符合条件的列。生成VT5-3表 ORDER BY 从VT5-3中的表中,根据ORDER BY 子句的条件对结果进行排序,生成VC6表。
SELECT C.customerid, COUNT(O.orderid) AS numorders FROM dbo.Customers AS C LEFT OUTER JOIN dbo.Orders AS O ON C.customerid = O.customerid WHERE C.city = 'Madrid' GROUP BY C.customerid HAVING COUNT(O.orderid) < 3 ORDER BY numorders
注意:由于数据现在还没有被分组,因此现在你不能使用聚合运算-例如:你不能使用这样的句子 WHERE orderdate = MAX(orderdate)。另外你也不能使用SELECT子句中创建的变量别名,因为现在还没有处理SELECT子句-例如你不能写这样的句子:SELECT YEAR(orderdate) AS orderyear . . . WHERE orderyear > 2008.
SELECT子句中的表达式可以返回或者操作前一步表中返回的基本列。如果这个sql语句是一个聚合查询,在Step 3之后,你只能使用GROUP BY中的列,对不属于GROUP集合中的列必须使用聚合运算。不属于FROM表中基本列的必须为其起一个别名,如YEAR(orderdate) AS orderyear。
注意:在SELECT子句中创建的别名,不能在之前的Step中使用,即使在SELECT子句中也不能。原因是sql的很多操作是同时操作(all at once operation),至于什么是all-at-once operation这里就不再介绍了。因此,SELECT子句中创建的别名只能在后面的子句中使用,如ORDER BY。例如:SELECT YEAR(orderdate) AS orderyear . . . ORDER BY orderyear。
在这个例子中:
复制代码 代码如下:
SELECT C.customerid, COUNT(O.orderid) AS numorders