Notice (8): file_put_contents(): Write of 271 bytes failed with errno=28 No space left on device [CORE/src/Log/Engine/FileLog.php, line 140]

        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 (8): SplFileObject::fwrite() [<a href='https://secure.php.net/splfileobject.fwrite'>splfileobject.fwrite</a>]: Write of 7651 bytes failed with errno=28 No space left on device [CORE/src/Cache/Engine/FileEngine.php, line 141]

Code Context

        $success = $this->_File->ftruncate(0) &&
            $this->_File->fwrite($contents) &&
            $this->_File->fflush();

SplFileObject::fwrite() - [internal], line ??
Cake\Cache\Engine\FileEngine::set() - CORE/src/Cache/Engine/FileEngine.php, line 141
Cake\I18n\TranslatorRegistry::get() - CORE/src/I18n/TranslatorRegistry.php, line 206
Cake\I18n\I18n::getTranslator() - CORE/src/I18n/I18n.php, line 148
__ - CORE/src/I18n/functions.php, line 45
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3420
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 (8): SplFileObject::fwrite() [<a href='https://secure.php.net/splfileobject.fwrite'>splfileobject.fwrite</a>]: Write of 5131 bytes failed with errno=28 No space left on device [CORE/src/Cache/Engine/FileEngine.php, line 141]

Code Context

        $success = $this->_File->ftruncate(0) &&
            $this->_File->fwrite($contents) &&
            $this->_File->fflush();

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 6433
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

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Code Context

        $success = $this->_File->ftruncate(0) &&
            $this->_File->fwrite($contents) &&
            $this->_File->fflush();

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\Table::getPrimaryKey() - CORE/src/ORM/Table.php, line 653
Cake\ORM\Query::_addAssociationsToTypeMap() - CORE/src/ORM/Query.php, line 507
Cake\ORM\Query::contain() - CORE/src/ORM/Query.php, line 462
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6433
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

Notice (8): SplFileObject::fwrite() [<a href='https://secure.php.net/splfileobject.fwrite'>splfileobject.fwrite</a>]: Write of 920 bytes failed with errno=28 No space left on device [CORE/src/Cache/Engine/FileEngine.php, line 141]

Code Context

        $success = $this->_File->ftruncate(0) &&
            $this->_File->fwrite($contents) &&
            $this->_File->fflush();

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 (8): SplFileObject::fwrite() [<a href='https://secure.php.net/splfileobject.fwrite'>splfileobject.fwrite</a>]: Write of 135 bytes failed with errno=28 No space left on device [CORE/src/Cache/Engine/FileEngine.php, line 141]

Code Context

        $success = $this->_File->ftruncate(0) &&
            $this->_File->fwrite($contents) &&
            $this->_File->fflush();

SplFileObject::fwrite() - [internal], line ??
Cake\Cache\Engine\FileEngine::set() - CORE/src/Cache/Engine/FileEngine.php, line 141
Cake\Cache\Cache::write() - CORE/src/Cache/Cache.php, line 266
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6766
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 3634
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

Warning (512): long cache was unable to write 'b660fefba714e2e84ce6fbe2e1743e3d' to Cake\Cache\Engine\FileEngine cache [CORE/src/Cache/Cache.php, line 275]

Code Context

                ),
                E_USER_WARNING
            );

Cake\Cache\Cache::write() - CORE/src/Cache/Cache.php, line 275
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6766
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 3634
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

Notice (8): SplFileObject::fwrite() [<a href='https://secure.php.net/splfileobject.fwrite'>splfileobject.fwrite</a>]: Write of 126 bytes failed with errno=28 No space left on device [CORE/src/Cache/Engine/FileEngine.php, line 141]

Code Context

        $success = $this->_File->ftruncate(0) &&
            $this->_File->fwrite($contents) &&
            $this->_File->fflush();

SplFileObject::fwrite() - [internal], line ??
Cake\Cache\Engine\FileEngine::set() - CORE/src/Cache/Engine/FileEngine.php, line 141
Cake\Cache\Cache::write() - CORE/src/Cache/Cache.php, line 266
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6766
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 3663
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

Warning (512): long cache was unable to write '5bf73fa0cd63eff1d1fc1724978e5464' to Cake\Cache\Engine\FileEngine cache [CORE/src/Cache/Cache.php, line 275]

Code Context

                ),
                E_USER_WARNING
            );

Cake\Cache\Cache::write() - CORE/src/Cache/Cache.php, line 275
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6766
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 3663
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

Notice (8): unserialize() [<a href='https://secure.php.net/function.unserialize'>function.unserialize</a>]: Error at offset 20416 of 20469 bytes [APP/Controller/NewsController.php, line 5571]

Code Context

               {
                      $a=unserialize($line2);
               }

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::view() - APP/Controller/NewsController.php, line 3698
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

Notice (8): SplFileObject::fwrite() [<a href='https://secure.php.net/splfileobject.fwrite'>splfileobject.fwrite</a>]: Write of 92838 bytes failed with errno=28 No space left on device [CORE/src/Cache/Engine/FileEngine.php, line 141]

Code Context

        $success = $this->_File->ftruncate(0) &&
            $this->_File->fwrite($contents) &&
            $this->_File->fflush();

SplFileObject::fwrite() - [internal], line ??
Cake\Cache\Engine\FileEngine::set() - CORE/src/Cache/Engine/FileEngine.php, line 141
Cake\Cache\Cache::write() - CORE/src/Cache/Cache.php, line 266
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6766
App\Controller\NewsController::get_data() - APP/Controller/NewsController.php, line 5701
App\Controller\NewsController::action_cache() - APP/Controller/NewsController.php, line 5493
App\Controller\NewsController::cache_action() - APP/Controller/NewsController.php, line 5281
App\Controller\NewsController::article_show() - APP/Controller/NewsController.php, line 4290
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3822
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

Warning (512): 1hours cache was unable to write 'de6109c1b8b43f5d3f3095be8d8c7194' to Cake\Cache\Engine\FileEngine cache [CORE/src/Cache/Cache.php, line 275]

Code Context

                ),
                E_USER_WARNING
            );

Cake\Cache\Cache::write() - CORE/src/Cache/Cache.php, line 275
App\Controller\NewsController::action_() - APP/Controller/NewsController.php, line 6766
App\Controller\NewsController::get_data() - APP/Controller/NewsController.php, line 5701
App\Controller\NewsController::action_cache() - APP/Controller/NewsController.php, line 5493
App\Controller\NewsController::cache_action() - APP/Controller/NewsController.php, line 5281
App\Controller\NewsController::article_show() - APP/Controller/NewsController.php, line 4290
App\Controller\NewsController::view() - APP/Controller/NewsController.php, line 3822
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

Practical cases of SQL Server database connection queries and sub queries

Database Operation Tutorial 2023-05-12 12:11:09 Source: Network

cataloguepreface1. Query the student ID, name, elective course ID, and grades of all students2

catalogue

preface
1. Query the student ID, name, elective course ID, and grades of all students
2. Search for elective courses with the name&quo; Database Principles and Applications; Student's student ID and name
3. Using aliases to query the student ID, name, elective course ID, and grades of all students
4. Query the names, genders, and ages of all students older than Zhang Wenbao
5. Use Format 2 to query the student ID, name, elective course ID, and grades of all students
6. Query the student ID, name, and corresponding course selection information of all students. If the student has not selected a course, the student ID and name also need to be displayed
7. Query the basic information of course selection students (if there are actually foreign key constraints, this situation does not exist)
8. Use the right outer link to query the student's student ID, elective course ID, course name, and credits, as well as list the course information for non student elective courses
9. Implement full external connection between student and sc tables
10. Query the age from the student table as‘ 19’ And‘ 20’ The department of the student, excluding duplicate rows
11. Query the age from the student table as‘ 19’ And‘ 20’ The department of the student, including duplicate rows
12. Search for student IDs and names of all elective courses
13. Query the student ID, name, and age of students who are older than the average age
14. Query the names and ages of students who are older than any student in the CS department
15. Query the course information of existing students' elective courses
16. Search for course information that no students have yet taken
17. Query the information of CS students and generate a new table temp
18. Generate a new table SCL for all student and course information
19. I have taken an elective course; Front Page Design” Increase student grades by 5 points in the course
20. Deleted elective courses; Front Page Design” Course selection information for the course
summary

Tip: Utilize simple single table queries and advanced multi table query skills, and flexibly use inner join queries, outer join queries, or sub queries according to query requirements. At the same time, it also utilizes two formats of inner join queries, three outer join query syntax formats, and sub query syntax formats.

preface

Inner join query (querying between different tables)

1. Query the student ID, name, elective course ID, and grades of all students

Method 1

USEXSCJGOSELECTstudent.sno,sname,cno,gradefromstudent,scwherestudent.sno=sc.sno

Method 2

USEXSCJGOSELECTstudent.sno,sname,cno,gradefromstudentjoinsconstudent.sno=sc.sno

2. Search for elective courses with the name&quo; Database Principles and Applications; Student's student ID and name

Method 1

USEXSCJselectstudent. sno, snamefrom student, sc, coursewherestudent. sno=sc. snoandsc. cno=course. cnonandcname='Database Principles and Applications'

Method 2

Selectstudent. sno, snamefrom studentjoinsconstudent. sno=sc. snojoincourseonsc. cno=course. cnowherecname='Database Principles and Applications'

3. Using aliases to query the student ID, name, elective course ID, and grades of all students

selectx.sno,sname,cno,gradefromstudentx,scywherex.sno=y.sno

Self connection query

4. Query the names, genders, and ages of all students older than Zhang Wenbao

Select A. sname, A. ssex, A. sage from studentA, studentBwhere B. sname='Zhang Wenbao' and A. sage> B.sage

Using the second format to implement inline queries (JOINON)

5. Use Format 2 to query the student ID, name, elective course ID, and grades of all students

SELECTstudent.sno,sname,cno,gradefromstudentjoinsconstudent.sno=sc.sno

External connection (left external connection)

6. Query the student ID, name, and corresponding course selection information of all students. If the student has not selected a course, the student ID and name also need to be displayed

SELECTstudent.sno,sname,cno,gradefromstudentleftouterjoinsconstudent.sno=sc.sno

Right outer connection

7. Query the basic information of course selection students (if there are actually foreign key constraints, this situation does not exist)

selectsc.sno,sname,cno,gradefromscrightouterjoinstudentonstudent.sno=sc.sno

8. Use the right outer link to query the student's student ID, elective course ID, course name, and credits, as well as list the course information for non student elective courses

selectsc.sno,course.cno,cname,creditfromscrightouterjoincourseoncourse.cno=sc.cno

Full external connection

9. Implement full external connection between student and sc tables

select*fromscfullouterjoinstudentonstudent.sno=sc.sno

UNION Joint Query

10. Query the age from the student table as‘ 19’ And‘ 20’ The department of the student, excluding duplicate rows

selectsdeptfromstudentwheresage='19'unionselectsdeptfromstudentwheresage='20'

11. Query the age from the student table as‘ 19’ And‘ 20’ The department of the student, including duplicate rows

selectsdeptfromstudentwheresage='19'unionallselectsdeptfromstudentwheresage='20'

Subqueries using IN or NOTIN

12. Search for student IDs and names of all elective courses

selectsno,snamefromstudentwheresnoin(selectsnofromsc)

Change to connection query implementation

selectdistinctstudent.sno,snamefromstudentjoinsconstudent.sno=sc.sno

Subqueries using comparison operators

13. Query the student ID, name, and age of students who are older than the average age

selectsno,sname,sagefromstudentwheresage> (selectAVG(sage)fromstudent)

Using any or all subqueries

14. Query the names and ages of students who are older than any student in the CS department

selectsname,sagefromstudentwheresage> any	(selectsagefromstudentwheresdept='CS')	ANDsdept!=' CS'select*fromstudent

Subqueries using EXISTS

15. Query the course information of existing students' elective courses

select*fromcoursewhereexists(select*fromscwherecourse.cno=sc.cno)

16. Search for course information that no students have yet taken

select*fromcoursewherenotexists(select*fromscwherecourse.cno=sc.cno)

View the course table

Extract data to another table

17. Query the information of CS students and generate a new table temp

select*intotempfromstudentwheresdept='CS'select*fromtemp

Subqueries in the Insert statement

18. Generate a new table SCL for all student and course information

INSERTINTOSCL(sno,cno)selectsno,cnofromstudent,course

Subqueries in UPDATE statements

19. I have taken an elective course; Front Page Design” Increase student grades by 5 points in the course

UPDATEscsetgrade=grade+5whencno=(selectcnoforomcoursewheresc. cno=course. cnonandcname='Frontend Page Design')

Delete subqueries in statements

20. Deleted elective courses; Front Page Design” Course selection information for the course

Deletefromscwhercno=(selectcnoforomcoursewheresc. cno=course. cnonandcname='Front Page Design ')

summary

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Practical cases of SQL Server database connection queries and sub queries

catalogue

preface

1. Query the student ID, name, elective course ID, and grades of all students

2. Search for elective courses with the name&quo; Database Principles and Applications; Student's student ID and name

3. Using aliases to query the student ID, name, elective course ID, and grades of all students

4. Query the names, genders, and ages of all students older than Zhang Wenbao

5. Use Format 2 to query the student ID, name, elective course ID, and grades of all students

6. Query the student ID, name, and corresponding course selection information of all students. If the student has not selected a course, the student ID and name also need to be displayed

7. Query the basic information of course selection students (if there are actually foreign key constraints, this situation does not exist)

8. Use the right outer link to query the student's student ID, elective course ID, course name, and credits, as well as list the course information for non student elective courses

9. Implement full external connection between student and sc tables

10. Query the age from the student table as‘ 19’ And‘ 20’ The department of the student, excluding duplicate rows

11. Query the age from the student table as‘ 19’ And‘ 20’ The department of the student, including duplicate rows

12. Search for student IDs and names of all elective courses

13. Query the student ID, name, and age of students who are older than the average age

14. Query the names and ages of students who are older than any student in the CS department

15. Query the course information of existing students' elective courses

16. Search for course information that no students have yet taken

17. Query the information of CS students and generate a new table temp

18. Generate a new table SCL for all student and course information

19. I have taken an elective course; Front Page Design” Increase student grades by 5 points in the course

20. Deleted elective courses; Front Page Design” Course selection information for the course

summary

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Practical cases of SQL Server database connection queries and sub queries

catalogue

preface

1. Query the student ID, name, elective course ID, and grades of all students

2. Search for elective courses with the name&quo; Database Principles and Applications; Student's student ID and name

3. Using aliases to query the student ID, name, elective course ID, and grades of all students

4. Query the names, genders, and ages of all students older than Zhang Wenbao

5. Use Format 2 to query the student ID, name, elective course ID, and grades of all students

6. Query the student ID, name, and corresponding course selection information of all students. If the student has not selected a course, the student ID and name also need to be displayed

7. Query the basic information of course selection students (if there are actually foreign key constraints, this situation does not exist)

8. Use the right outer link to query the student's student ID, elective course ID, course name, and credits, as well as list the course information for non student elective courses

9. Implement full external connection between student and sc tables

10. Query the age from the student table as‘ 19’ And‘ 20’ The department of the student, excluding duplicate rows

11. Query the age from the student table as‘ 19’ And‘ 20’ The department of the student, including duplicate rows

12. Search for student IDs and names of all elective courses

13. Query the student ID, name, and age of students who are older than the average age

14. Query the names and ages of students who are older than any student in the CS department

15. Query the course information of existing students' elective courses

16. Search for course information that no students have yet taken

17. Query the information of CS students and generate a new table temp

18. Generate a new table SCL for all student and course information

19. I have taken an elective course; Front Page Design” Increase student grades by 5 points in the course

20. Deleted elective courses; Front Page Design” Course selection information for the course

summary

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