mybatis分页插件pagehelper，当sql中含有if时报错

1 背景说明

今天在使用mybatis的分页插件pagehelper时发现了一个问题，就是当sql中有 if(sum()条件,xx,xx) 的时候程序报错。我把sql直接拷贝出来执行是没问题的，弄了一个下午最终解决了。百度、谷歌了很久都没找到解决办法，最终一点点的实验，终于发现了问题所在。
也希望有同样问题的人少走弯路

2 报错信息

• 我的代码（mybatis的mapper.xml文件）

<select id="queryAAAA" parameterType="java.util.Map" resultType="cc.xxx.xxx.entity.AAAAAAAA">
	SELECT
		a.time_id 'date_time',
		SUM(a.calls) 'call_num',
		SUM(a.ans_calls) 'talk_num',
		IF(SUM(a.calls) = 0,0,SUM(a.ans_calls) / SUM(a.calls)) 'talk_rate'
	FROM
	agg_c_fact_agent_detail_hour a
	<where>
	    1=1
	where>
	GROUP BY
		a.time_id,
		a.agent_no,
		a.call_type
select>

• 错误日志

### Error querying database.  Cause: com.github.pagehelper.PageException: 处理排序失败: net.sf.jsqlparser.JSQLParserException
### The error may exist in file [D:\6Report\2.0\rpt-service\target\classes\mapper\Report.xml]
### The error may involve cc.wellcloud.rpt.dao.ReportDao.queryAgentOutbound_COUNT
### The error occurred while handling results
### SQL: select count(0) from (SELECT    a.time_id 'date_time',    SUM(a.calls) 'call_num',    SUM(a.ans_calls) 'talk_num',    IF(SUM(a.calls) = 0,0,SUM(a.ans_calls) / SUM(a.calls)) 'talk_rate'   FROM   agg_c_fact_agent_detail_hour a    WHERE 1=1           and a.time_id >= ?          and a.time_id <= ?                and a.tenant_id = ?    GROUP BY    a.time_id,    a.agent_no,    a.call_type) tmp_count
### Cause: com.github.pagehelper.PageException: 处理排序失败: net.sf.jsqlparser.JSQLParserException
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30) ~[mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:150) ~[mybatis-3.4.6.jar:3.4.6]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141) ~[mybatis-3.4.6.jar:3.4.6]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_131]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_131]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_131]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_131]
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433) ~[mybatis-spring-1.3.2.jar:1.3.2]
	... 108 common frames omitted
Caused by: com.github.pagehelper.PageException: 处理排序失败: net.sf.jsqlparser.JSQLParserException
	at com.github.pagehelper.parser.OrderByParser.converToOrderBySql(OrderByParser.java:64) ~[pagehelper-5.1.8.jar:na]
	at com.github.pagehelper.dialect.AbstractHelperDialect.getPageSql(AbstractHelperDialect.java:173) ~[pagehelper-5.1.8.jar:na]
	at com.github.pagehelper.PageHelper.getPageSql(PageHelper.java:98) ~[pagehelper-5.1.8.jar:na]
	at com.github.pagehelper.util.ExecutorUtil.pageQuery(ExecutorUtil.java:168) ~[pagehelper-5.1.8.jar:na]
	at com.github.pagehelper.PageInterceptor.intercept(PageInterceptor.java:104) ~[pagehelper-5.1.8.jar:na]
	at org.apache.ibatis.plugin.Plugin.invoke(Plugin.java:61) ~[mybatis-3.4.6.jar:3.4.6]
	at com.sun.proxy.$Proxy128.query(Unknown Source) ~[na:na]
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148) ~[mybatis-3.4.6.jar:3.4.6]
	... 114 common frames omitted
Caused by: net.sf.jsqlparser.JSQLParserException: null
	at net.sf.jsqlparser.parser.CCJSqlParserUtil.parse(CCJSqlParserUtil.java:55) ~[jsqlparser-1.2.jar:na]
	at com.github.pagehelper.parser.OrderByParser.converToOrderBySql(OrderByParser.java:52) ~[pagehelper-5.1.8.jar:na]
	... 121 common frames omitted
Caused by: net.sf.jsqlparser.parser.ParseException: Encountered unexpected token: "IF" "IF"
    at line 5, column 4.

Was expecting one of:

    "*"
    "+"
    "-"
    "?"
    "@"
    "@@"
    "ACTION"
    "ANY"
    "CASCADE"
    "CASE"
    "CAST"
    "COLUMN"
    "COMMIT"
    "DO"
    "ENABLE"
    "END"
    "EXTRACT"
    "FIRST"
    "FOLLOWING"
    "GROUP_CONCAT"
    "INDEX"
    "INSERT"
    "INTERVAL"
    "KEY"
    "LAST"
    "MATERIALIZED"
    "NO"
    "NULL"
    "NULLS"
    "OPEN"
    "OVER"
    "PARTITION"
    "PERCENT"
    "PRECISION"
    "PRIMARY"
    "PRIOR"
    "RANGE"
    "REPLACE"
    "ROW"
    "ROWS"
    "SEPARATOR"
    "SIBLINGS"
    "TABLE"
    "TEMP"
    "TEMPORARY"
    "TRUNCATE"
    "UNSIGNED"
    "VALUE"
    "VALUES"
    "XML"
    "{d"
    "{t"
    "{ts"
    "~"
    
    
    
    
    
    
    
    

	at net.sf.jsqlparser.parser.CCJSqlParser.generateParseException(CCJSqlParser.java:18047) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.jj_consume_token(CCJSqlParser.java:17900) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.PrimaryExpression(CCJSqlParser.java:7394) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.BitwiseXor(CCJSqlParser.java:7161) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.MultiplicativeExpression(CCJSqlParser.java:7119) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.AdditiveExpression(CCJSqlParser.java:7082) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.BitwiseAndOr(CCJSqlParser.java:7028) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.ConcatExpression(CCJSqlParser.java:7004) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.SimpleExpression(CCJSqlParser.java:6997) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.SelectExpressionItem(CCJSqlParser.java:3377) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.SelectItem(CCJSqlParser.java:3523) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.SelectItemsList(CCJSqlParser.java:3368) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.PlainSelect(CCJSqlParser.java:2930) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.SetOperationList(CCJSqlParser.java:3107) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.SelectBody(CCJSqlParser.java:2824) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.Select(CCJSqlParser.java:2817) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.SingleStatement(CCJSqlParser.java:133) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParser.Statement(CCJSqlParser.java:81) ~[jsqlparser-1.2.jar:na]
	at net.sf.jsqlparser.parser.CCJSqlParserUtil.parse(CCJSqlParserUtil.java:53) ~[jsqlparser-1.2.jar:na]
	... 122 common frames omitted

3 版本说明

-mybatis版本
<dependency>
    <groupId>org.mybatis.spring.bootgroupId>
    <artifactId>mybatis-spring-boot-starterartifactId>
    <version>1.3.2version>
dependency>

- mybatis分页插件版本
<dependency>
    <groupId>com.github.pagehelpergroupId>
    <artifactId>pagehelper-spring-boot-starterartifactId>
    <version>1.2.10version>
dependency>

4 报错演示

（1）经过多次尝试，考虑了不同情况，得到如下图：

（2）得出结论：
当且仅当 if() 的条件有sum()聚合函数时报错（其他的聚合函数还没试过）

5解决办法

5.1方案一：使用 case when代替if

例如：

CASE WHEN SUM(a.calls)=0 THEN 0 ELSE SUM(a.ans_calls) / SUM(a.calls) END 'talk_rate'

5.2方案二：把pagehelper升级到最新（最推荐）

• （我后来才发现的，浪费一个下午时间，尴尬-_-，这个应该是低版本的bug）
  升级到如下版本：

<dependency>
    <groupId>com.github.pagehelpergroupId>
    <artifactId>pagehelper-spring-boot-starterartifactId>
    <version>1.2.12version>
dependency>

• 方案二完美解决