select exists return multi results

## Bug Report

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- Searched open and closed [GitHub issues](https://github.com/apache/shardingsphere/issues).
- Read documentation: [ShardingSphere Doc](https://shardingsphere.apache.org/document/current/en/overview).

Please pay attention on issues you submitted, because we maybe need more details.
If no response anymore and we cannot reproduce it on current information, we will **close it**.

Please answer these questions before submitting your issue. Thanks!

### Which version of ShardingSphere did you use?
5.2.0

### Which project did you use? ShardingSphere-JDBC or ShardingSphere-Proxy?
ShardingSphere-JDBC

### Expected behavior
return true or false

### Actual behavior
throw exception below:
```
2022-10-15 15:48:20.745 ERROR 6488 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 2] with root cause

org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 2
at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:80) ~[mybatis-3.5.6.jar:3.5.6]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_201]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_201]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_201]
at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:426) ~[mybatis-spring-2.0.5.jar:2.0.5]
at com.sun.proxy.$Proxy61.selectOne(Unknown Source) ~[na:na]
at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:159) ~[mybatis-spring-2.0.5.jar:2.0.5]
at com.baomidou.mybatisplus.core.override.MybatisMapperMethod.execute(MybatisMapperMethod.java:90) ~[mybatis-plus-core-3.4.2.jar:3.4.2]
at com.baomidou.mybatisplus.core.override.MybatisMapperProxy$PlainMethodInvoker.invoke(MybatisMapperProxy.java:148) ~[mybatis-plus-core-3.4.2.jar:3.4.2]
at com.baomidou.mybatisplus.core.override.MybatisMapperProxy.invoke(MybatisMapperProxy.java:89) ~[mybatis-plus-core-3.4.2.jar:3.4.2]
at com.sun.proxy.$Proxy65.existsOrderAsByOrderId(Unknown Source) ~[na:na]
at com.example.demo.rest.OrderController.orderExists(OrderController.java:22) ~[classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_201]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_201]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_201]
at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_201]
at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:626) ~[tomcat-embed-core-9.0.41.jar:4.0.FR]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at javax.servlet.http.HttpServlet.service(HttpServlet.java:733) ~[tomcat-embed-core-9.0.41.jar:4.0.FR]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.41.jar:9.0.41]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.2.12.RELEASE.jar:5.2.12.RELEASE]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:888) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1597) [tomcat-embed-core-9.0.41.jar:9.0.41]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.41.jar:9.0.41]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_201]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_201]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.41.jar:9.0.41]
at java.lang.Thread.run(Thread.java:748) [na:1.8.0_201]

```

### Reason analyze (If you can)
ShardingSphere-JDBC just does a union on the `exists` result of the sharding tables and returns two row

### Steps to reproduce the behavior, such as: SQL to execute, sharding rule configuration, when exception occur etc.
```
@Select("select exists(select * from t_order where order_name=#{orderName} limit 1) as c")
boolean existsOrderAsByOrderId(@Param("orderName") String orderName);
```

### Example codes for reproduce this issue (such as a github link).
[https://github.com/CatInRl/sharding-jdbc-demo](https://github.com/CatInRl/sharding-jdbc-demo)
`curl 127.0.0.1:8080/order/exists?orderName=order1`