Java android会话变量答案

【问题标题】：Java android session variableJava android会话变量
【发布时间】：2019-10-16 11:21:57
【问题描述】：

我尝试这样做。

在我的表中，我有一行 lp，我尝试这样做：

@Query("set @i = 0; SELECT @i:=@i+1, ad.* * FROM added_note ad where order_id = :order_id and commission_id = 0")
LiveData<List<NoteEntity>> findNotesByOrder(long order_id);

但它不起作用。当我尝试构建时，我的应用程序无法运行且无法编译。我看到一个错误

这是我的错误：

org.gradle.api.internal.tasks.compile.CompilationFailedException: Compilation failed; see the compiler error output for details.
    at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:52)
    at org.gradle.api.internal.tasks.compile.JdkJavaCompiler.execute(JdkJavaCompiler.java:37)
    at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.delegateAndHandleErrors(NormalizingJavaCompiler.java:98)
    at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute(NormalizingJavaCompiler.java:51)
    at org.gradle.api.internal.tasks.compile.NormalizingJavaCompiler.execute(NormalizingJavaCompiler.java:37)
    at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.execute(CleaningJavaCompilerSupport.java:35)
    at org.gradle.api.internal.tasks.compile.CleaningJavaCompilerSupport.execute(CleaningJavaCompilerSupport.java:25)
    at org.gradle.api.internal.tasks.compile.incremental.IncrementalResultStoringDecorator.execute(IncrementalResultStoringDecorator.java:41)
    at org.gradle.api.internal.tasks.compile.incremental.IncrementalResultStoringDecorator.execute(IncrementalResultStoringDecorator.java:27)
    at org.gradle.api.internal.tasks.compile.incremental.IncrementalAnnotationProcessingCompiler.execute(IncrementalAnnotationProcessingCompiler.java:50)
    at org.gradle.api.internal.tasks.compile.incremental.IncrementalAnnotationProcessingCompiler.execute(IncrementalAnnotationProcessingCompiler.java:36)
    at org.gradle.api.tasks.compile.JavaCompile.performCompilation(JavaCompile.java:156)
    at org.gradle.api.tasks.compile.JavaCompile.compile(JavaCompile.java:126)
    at com.android.build.gradle.tasks.factory.AndroidJavaCompile.compile(AndroidJavaCompile.java:92)
    at sun.reflect.GeneratedMethodAccessor803.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)
    at org.gradle.api.internal.project.taskfactory.IncrementalTaskAction.doExecute(IncrementalTaskAction.java:50)
    at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:39)
    at org.gradle.api.internal.project.taskfactory.StandardTaskAction.execute(StandardTaskAction.java:26)
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$1.run(ExecuteActionsTaskExecuter.java:124)
    at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
    at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
    at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:199)
    at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:110)
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:113)
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:95)
    at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:73)
    at org.gradle.api.internal.tasks.execution.OutputDirectoryCreatingTaskExecuter.execute(OutputDirectoryCreatingTaskExecuter.java:51)
    at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:59)
    at org.gradle.api.internal.tasks.execution.ResolveTaskOutputCachingStateExecuter.execute(ResolveTaskOutputCachingStateExecuter.java:54)
    at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:59)
    at

【问题讨论】：

什么不起作用？你收到错误了吗？
@grrigore 没有编译
所以有错误。它说什么？
@grrigore 我编辑我的帖子
@grrigore an error is error: Must have exactly 1 query in @Query value

标签： java android android-room

【解决方案1】：

我相信该消息是说您有一个 ';'（分号），因此您正在尝试运行 2 个查询。你不能。

但是，SELECT 之前的部分，即set @i = 0;，如果删除分号会导致失败（除非这是我没有遇到的一些功能）。它似乎是 SQLite UPDATE 语句的 SET 部分，如果是这样，它是无效的 SQLite。由于建议整个查询只是猜测，因此没有建议修复。

【讨论】：