이차 방정식에서 D > =0 이면 두 실근 D < 0 이면 허근인것처럼  c1v1 + c2v2 + ... + cpvp=0 식에서 trivial solution만 가지고 있으면 independence non-trivial solution도 가지고 있으면 dependence 라는 판별식 처럼 생각하면 되는건지.. https://en.wikipedia.org/wiki/Linear_independence#:~:text=In%20the%20theory%20of%20vector,said%20to%20be%20linearly%20independent. dependence와 independence의 의미가 이해가 잘 안되서 위키에서 찾아보니  R3에서 {u, v, w}벡터 셋이 있을때 u, v벡터로 나머지 벡터 w를 표현할수 없는?것을 independent {u, v, w}벡터 셋이 있을때 u, v벡터로 w를 표현할 수 있을때를 dependent라고 이해를 했는데 올바르게 이해한건지 궁금합니다.

LEFT JOIN을 했을경우 Customers를 기준으로 Orders를 붙이되 Order이 존재하지않는 Customer은 Orders부분에 NULL이 나오는것 까지는 이해가 되었습니다. 하지만 그림에처럼 CustomerID까지 NULL이 나오는 이유는 무엇인가용? Order은 존재하지 않지만 CustomerID는 회원이라면 기본적으로 존재하는것 아닌가요?!

강사님.... 스프링 데이터 JPA 편 듣고있는데 진짜 있는그대로 얼마안되는 코드 토씨하나 안틀리고 썼는데....심각한 오류가 발생했는데 도저히못찾겠어요 뭐가 문제인건지 모르겠습니다.... 그전강의 JPA 강의보면서 로직짜볼떈 아무이상없었는데 스프링 데이터 JPA를 쓰려고 필요없는거 삭제하고 인터페이스만들고 나온내용대로 따라했더니 치명적인오류가 나오는데.....이게 어디서부터 뭐가잘못되었는지 아무리찾아봐도 알 수가 없어요ㅠㅜ 혹시몰라서 제가 오류난 부분을 Console 창 복사해서 여기에 남깁니다...... ------------------------------------------------------------------------------------------------- java.lang.IllegalStateException: Failed to load ApplicationContext at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:132) at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:123) at org.springframework.test.context.web.ServletTestExecutionListener.setUpRequestContextIfNecessary(ServletTestExecutionListener.java:190) at org.springframework.test.context.web.ServletTestExecutionListener.prepareTestInstance(ServletTestExecutionListener.java:132) at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:244) at org.springframework.test.context.junit.jupiter.SpringExtension.postProcessTestInstance(SpringExtension.java:98) at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeTestInstancePostProcessors$5(ClassBasedTestDescriptor.java:341) at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.executeAndMaskThrowable(ClassBasedTestDescriptor.java:346) at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$invokeTestInstancePostProcessors$6(ClassBasedTestDescriptor.java:341) at java.base/java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:195) at java.base/java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:177) at java.base/java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1655) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) at java.base/java.util.stream.StreamSpliterators$WrappingSpliterator.forEachRemaining(StreamSpliterators.java:312) at java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:735) at java.base/java.util.stream.Streams$ConcatSpliterator.forEachRemaining(Streams.java:734) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:658) at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.invokeTestInstancePostProcessors(ClassBasedTestDescriptor.java:340) at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.instantiateAndPostProcessTestInstance(ClassBasedTestDescriptor.java:263) at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$2(ClassBasedTestDescriptor.java:256) at java.base/java.util.Optional.orElseGet(Optional.java:369) at org.junit.jupiter.engine.descriptor.ClassBasedTestDescriptor.lambda$testInstancesProvider$3(ClassBasedTestDescriptor.java:255) at org.junit.jupiter.engine.execution.TestInstancesProvider.getTestInstances(TestInstancesProvider.java:29) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$prepare$0(TestMethodTestDescriptor.java:108) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:107) at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.prepare(TestMethodTestDescriptor.java:71) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$prepare$1(NodeTestTask.java:107) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.prepare(NodeTestTask.java:107) at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:75) at java.base/java.util.ArrayList.forEach(ArrayList.java:1541) at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125) at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122) at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80) at java.base/java.util.ArrayList.forEach(ArrayList.java:1541) at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.invokeAll(SameThreadHierarchicalTestExecutorService.java:38) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$5(NodeTestTask.java:139) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$7(NodeTestTask.java:125) at org.junit.platform.engine.support.hierarchical.Node.around(Node.java:135) at org.junit.platform.engine.support.hierarchical.NodeTestTask.lambda$executeRecursively$8(NodeTestTask.java:123) at org.junit.platform.engine.support.hierarchical.ThrowableCollector.execute(ThrowableCollector.java:73) at org.junit.platform.engine.support.hierarchical.NodeTestTask.executeRecursively(NodeTestTask.java:122) at org.junit.platform.engine.support.hierarchical.NodeTestTask.execute(NodeTestTask.java:80) at org.junit.platform.engine.support.hierarchical.SameThreadHierarchicalTestExecutorService.submit(SameThreadHierarchicalTestExecutorService.java:32) at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:57) at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:51) at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:248) at org.junit.platform.launcher.core.DefaultLauncher.lambda$execute$5(DefaultLauncher.java:211) at org.junit.platform.launcher.core.DefaultLauncher.withInterceptedStreams(DefaultLauncher.java:226) at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:199) at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:132) at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:71) at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33) at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:220) at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:53) Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'memberController' defined in file [C:\Spring_kmh_20200928\Workspace\hello-spring\hello-spring\out\production\classes\hello\hellospring\Controller\MemberController.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'springConfig' defined in file [C:\Spring_kmh_20200928\Workspace\hello-spring\hello-spring\out\production\classes\hello\hellospring\SpringConfig.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'springDataJpaMemberRepository' defined in hello.hellospring.repository.SpringDataJpaMemberRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Cannot resolve reference to bean 'jpaMappingContext' while setting bean property 'mappingContext'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jpaMappingContext': Invocation of init method failed; nested exception is org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment] at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:797) at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:227) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1356) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1203) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:556) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:897) at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:879) at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) at org.springframework.boot.test.context.SpringBootContextLoader.loadContext(SpringBootContextLoader.java:120) at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:99) at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:124) ... 63 more Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'springConfig' defined in file [C:\Spring_kmh_20200928\Workspace\hello-spring\hello-spring\out\production\classes\hello\hellospring\SpringConfig.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'springDataJpaMemberRepository' defined in hello.hellospring.repository.SpringDataJpaMemberRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Cannot resolve reference to bean 'jpaMappingContext' while setting bean property 'mappingContext'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jpaMappingContext': Invocation of init method failed; nested exception is org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment] at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:797) at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:227) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.autowireConstructor(AbstractAutowireCapableBeanFactory.java:1356) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1203) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:556) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:408) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1336) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1176) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:556) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1307) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1227) at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:884) at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:788) ... 82 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'springDataJpaMemberRepository' defined in hello.hellospring.repository.SpringDataJpaMemberRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration: Cannot resolve reference to bean 'jpaMappingContext' while setting bean property 'mappingContext'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jpaMappingContext': Invocation of init method failed; nested exception is org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment] at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:342) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:113) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1697) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1442) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1307) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1227) at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:884) at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:788) ... 105 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jpaMappingContext': Invocation of init method failed; nested exception is org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1794) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594) at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:330) ... 119 more Caused by: org.hibernate.service.spi.ServiceException: Unable to create requested service [org.hibernate.engine.jdbc.env.spi.JdbcEnvironment] at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:275) at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237) at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:152) at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286) at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243) at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214) at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:176) at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:118) at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.metadata(EntityManagerFactoryBuilderImpl.java:1224) at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:1255) at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:58) at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:391) at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628) at java.base/java.lang.Thread.run(Thread.java:834) Caused by: org.hibernate.HibernateException: Access to DialectResolutionInfo cannot be null when 'hibernate.dialect' not set at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.determineDialect(DialectFactoryImpl.java:100) at org.hibernate.engine.jdbc.dialect.internal.DialectFactoryImpl.buildDialect(DialectFactoryImpl.java:54) at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:137) at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35) at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101) at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263) ... 17 more

형제 요소중에 이전 이후인지 아니면 가르키고잇는 요소에 이전 이후 인지 궁금합니다.. 검색 해보았는데 형제인지 아닌지는 명확히 찾기가 어렵네요 ㅠ

공격자를 크로미움 admin 을 크롬으로 사용하고 개인정보 수정 글을 쓰고 클릭하면 크로미움은 가능한데 크롬은 회원정보 수정 완료 팝업창 이후 존재하지 않는 사용자입니다가 뜨면서 바뀌지 않네요 무슨 문제일까요?..

문제 내용이 쫌 다르지만 같은 문제는 맞는거 같습니다. 혹시나 현행화되지 않아 당황하시는 분들이 계실까봐 알려드립니다.

안녕하세요~ 강의 잘 듣고 있습니다! 7:45 경 작성하는 useEffect 부수함수에 관해서 질문이 있는데요.  새로고침 말고, 홈페이지에서 검색을 통해 유저 페이지로 넘어가는 경우에, 아래의 코드 때문에 user가 store에 저장됩니다. 근데 방금 작성한 useEffect 훅의 부수 함수가 user를 받아와서 다시 store에 저장하더라구요. 중복이 발생했는데 큰 문제가 없을까요? // SearchInput.js function goToUser(value) { const user = autoCompletes.find((item) => item.name === value); if (user) { dispatch(userActions.setValue('user', user)); // setValue 액션이 SearchInput 컴포넌트에서 먼저 발생 history.push(`/user/${user.name}`); } }

1, 위에 2개의 matrix도 Reduced Echelon Form으로 볼 수 있을까요?맨 왼쪽 Column은 pivot column이라는 말에 이와 같은 의문이 생겼습니다2. pivot position제가 이해한 바 로는 pivot position은 echelon form이 아닌 "reduced echelon form"에서 각 row의 leading entry를 pivot position이라고 이해했는데 이렇게 이해하는게 맞을까요?위에 다른분 질문으로 보다보니 [0 0 0 0 0 0 0 0 0] 이렇게 all zeros 인 경우에도 pivot postion이 있을 수 있는지 궁금해졌습니다.

마스크를 씌운뒤 적용부분을 지정했는데 그라디언트가 적용이 안되요. 그라디언트 툴을 눌러도 마우스부분에 x 라고 뜨는데 이건 왜인가요?

array_reduce의 인자중 use라는 키워드가 어떤 의미로 사용되는 키워드인지 알수 있을까요?

(사진)

dom기초에 대한 부분에서 dom 접근 함수에서  document.getElementById(elementId) 관련 예시에서 구글로고에 대한것을 아래 그림과 같이 했었는데, 저는 null이라고만 뜨는게 어떤게 잘못됐고, 어떻게 고쳐야 하는지 설명 부탁드리겠습니다. (참고로 저는 맥북을 사용하고 있고 크롬-개발자도구를 이용하였습니다!)

# 중복 순열 구하기 def DFS(L):     global cnt     if L == m:         cnt += 1         d.append(res) <- 이부분을 하면 모든 res가 추가된 리스트가 생성되지 않습니다              else:         for i in range(1, n+1):             if ch[i] == 0:                 ch[i] = 1                 res[L] = i                 DFS(L+1)                 ch[i]= 0 # 상위 레벨로 갈때 다시 초기화해준다 if __name__ == "__main__":     n, m = map(int, input().split())     res = [0] *n     ch = [0] * (n+1)     d = []     cnt = 0     DFS(0) DFS를 통해 구한 res들을 특정 list에 저장해서 메인 함수에서 사용하고 싶습니다. 방법이 있을까요 ?ㅠ

ID 가  더 큰 개념이라고 배웠는데 클래스안에 ID가 들어가도 상관없나요?

tupledata = ('fun-coding1', 'fun-coding2', 'fun-coding3', 'fun-coding4', 'fun-coding5') print(tupledata[1:6]) ('fun-coding2', 'fun-coding3', 'fun-coding4', 'fun-coding5')튜플 그대로 실행해도 이렇게 실행값이 제대로 나옵니다. 근데 선생님께서 튜플은 리스트처럼 변환하거나 이런게 안된다고 하셨는데 이렇게 인덱스를 적용하는 것이 가능한가요?

안녕하세요 강의 4-8 사가패턴과 Q&A 부분 2:17초 부근에서  export const LOG_OUT_REQUEST = 'LOG_OUT_REQUEST' 줄을 여러줄 복제하시고LOG_OUT_REQUEST  에서 REQUEST 부분을 마우스로 선택하시고 수정하시니 변수명 옆의 값도 동시에 수정되어지셨는데요이거 어떻게 하신 건지 알 수 있을까요? 

간단 명료하게 1.8버전 부터는 레플리케이션컨트롤러 배제하고 레플리카셋만 사용하면 되는 건가요? 아니면 아직 레플리케이션컨트롤러가 쓰일때가 있나요?

안녕하세요 영한님, 강의 잘 듣고있습니다. 혼자 프로젝트를 만드는중에 궁금한점이 생겨 질문드립니다. 강의에서 최대한 setter를 쓰지 않는 쪽으로 만드는게 좋다하셔서 모든 객체에 setter를 빼고 진행중인데요, setter를 뺐을 때, 그 기능을 대신하는 메소드를 해당 객체에 만들어 직접 변경해주는걸로 알고있습니다 예) public void changeName (String name){ this.name = name; } 그래서 이 방식으로 객체를 생성하려고 메소드를 만들어봤습니다.  private final Team team; public Long save(Long id, String name, String task, Company company) {Team team2 = team.createTeam(id, name, task, company); return teamRepository.save(team);} public Team createTeam(Long id, String name, String task, Company company) { this.id = id; this.name = name; this.task = task; this.company = company; company.addTeam(this); return this;} 생성메소드에 해당하는 createTeam을 강의에서는 static을 주고 setter를 사용해서 생성했는데, static을 사용하자니 this를 이용해서 값을 세팅할수 없었습니다. 모든 변수를 다 static으로 주면 된다는데 그건 너무 복잡해질것같고, 일단 Team team을 만들어서 해결했습니다. 여기서 코드를 더 줄여보고싶은데 혹시 Team team을 만들지않고 해결하는 방법이있나요?

yield 키워드를 return 키워드 대신에 사용하는 이유가 궁금합니다! return 으로 해보면 Request object is not iterable 이라고 뜨는데 제네레이터인 함수한테는 return 키워드를 아예 사용할 수 없는건가요?

안녕하세요. 강의 수강 중에 Haar 2번째 강의 영상에서는 OPENCV 폴더가 따로 있던데요. pip install opencv-python 으로 opencv를 설치했는데 저는 그와 같은 폴더가 없습니다. 추가로 설치해야하는게 있나요..?