首先，这个问题并没有影响代码执行，查询的数据是正确的。但是报错信息太长，让我觉得难受，所以研究了下怎么改。

报错信息

太长了，中间部分省略。

net.sf.jsqlparser.JSQLParserException
	at net.sf.jsqlparser.parser.CCJSqlParserUtil.parse(CCJSqlParserUtil.java:56)
	at com.github.pagehelper.parser.OrderByParser.converToOrderBySql(OrderByParser.java:51)
	at com.github.pagehelper.dialect.AbstractHelperDialect.getPageSql(AbstractHelperDialect.java:176)
	...
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:564)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
	...
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:564)
	at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:344)
	...
	at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: net.sf.jsqlparser.parser.ParseException: Encountered " <S_CHAR_LITERAL> "\'type\' "" at line 2, column 71.
Was expecting one of:
    "DO" ...
    "ANY" ...
    "KEY" ...
    "PERCENT" ...
    "END" ...
    "OPEN" ...
    "TABLE" ...
    ...
    "NO" ...
    "ACTION" ...
    <K_DATETIMELITERAL> ...
    "PRECISION" ...
    <S_IDENTIFIER> ...
    <S_QUOTED_IDENTIFIER> ...
	at net.sf.jsqlparser.parser.CCJSqlParser.generateParseException(CCJSqlParser.java:16395)

定位

根据上面的信息，定位到报错的位置是我的某个mapper中的某个函数。对应的mysql语句是正确，内容大概如下：

select s.id , 'sgrna' as 'type' from sys_sgrna_order s limit 5;

问题就出在 ‘sgrna’ as ‘type’ 这里。经过搜索，发现只要在pom中引入一个依赖即可。

<dependency>
	<groupId>com.github.jsqlparser</groupId>
	<artifactId>jsqlparser</artifactId>
	<version>4.6</version>
</dependency>

有的博客说需要在mapper中增加注解：@SqlParser(filter=true)

亲测，我这里不需要。

报错：java.lang.NoSuchMethodError: net.sf.jsqlparser.statement.select.PlainSelect.getGroupByColumnReferences()

org.springframework.web.util.NestedServletException: Handler dispatch failed; nested exception is java.lang.NoSuchMethodError: net.sf.jsqlparser.statement.select.PlainSelect.getGroupByColumnReferences()Ljava/util/List;
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1006)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:877)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.springframework.web.servlet.resource.ResourceUrlEncodingFilter.doFilter(ResourceUrlEncodingFilter.java:60)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
...

这个是因为pagehelper与jsqlparser的版本不一致，我改成下面这样就ok了（全部使用最新版本）。

<dependency>
	<groupId>com.github.jsqlparser</groupId>
	<artifactId>jsqlparser</artifactId>
	<version>4.6</version>
</dependency>
<!--pagehelper-->
<dependency>
	<groupId>com.github.pagehelper</groupId>
	<artifactId>pagehelper-spring-boot-autoconfigure</artifactId>
	<version>1.4.6</version>
</dependency>
<dependency>
    <groupId>com.github.pagehelper</groupId>
    <artifactId>pagehelper-spring-boot-starter</artifactId>
	<version>1.4.6</version>
</dependency>