在做一个校验操作的时候遇到的错误，报错如下，貌似是说本希望返回一个结果或是空值，结果发现了15个结果

Question

 Caused by: org.apache.ibatis.exceptions.TooManyResultsException: Expected one result (or null) to be returned by selectOne(), but found: 15
    at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:66)
    at sun.reflect.GeneratedMethodAccessor70.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:354)
    ... 76 more

接口中代码
 public Boolean hasThisKwordId(String KwordId)throws Exception;
 public String findLastKwordId(String parentid)throws Exception;
Controller中代码
@RequestMapping(value="/validate")
    @ResponseBody
    public Object validateKwords() throws Exception {
        PageData pd = new PageData();       
        Map<String,Object> map = new HashMap<String,Object>();
        pd = this.getPageData();
        if (kwordsService.findById(pd)!=null) {
            map.put("msg", "true");
        }else{
            map.put("msg", "false");
        }
        return AppUtil.returnObject(pd, map);
    }
    @RequestMapping(value="/findkwordid")
    @ResponseBody
    public Object findKwordId() throws Exception{
        PageData pd = new PageData();       
        Map<String,Object> map = new HashMap<String,Object>();
        pd = this.getPageData();
        String nextKwordid=getNextKwordId(pd.getString("parentid"));
        map.put("nextKwordid", nextKwordid);
        return AppUtil.returnObject(pd, map);
    }
        private String getNextKwordId(String parentid) throws Exception {
        String lastKwordId=kwordsService.findLastKwordId(parentid);
        String nextKwordId="";
        if (StringUtil.isNullOrEmpty(lastKwordId)) {
            nextKwordId=CodeConst.KWORDS_KWORDID_ROOT.equals(parentid)
                          ?CodeConst.KWORDS_KWORDID_START
                          :parentid+CodeConst.KWORDS_KWORDID_START;
        }else {
            if (lastKwordId.length()>CodeConst.KWORDS_KWORDID_INTERVAL) {
                nextKwordId=parentid+StringUtil.haoAddOne(lastKwordId.substring(lastKwordId.length()-CodeConst.KWORDS_KWORDID_INTERVAL,lastKwordId.length()),CodeConst.KWORDS_KWORDID_FORMAT);
            }else {
                nextKwordId=StringUtil.haoAddOne(lastKwordId, CodeConst.KWORDS_KWORDID_FORMAT);
            }
        }
        return nextKwordId;
    }
Mapper中代码
    <select id="hasThisKwordId" parameterType="String" resultType="int">
        select 
        count(0)
        from 
        <include refid="tableName"></include>
        where 
            KWORDID = #{KWORDID}
    </select>
    <select id="findLastKwordId" parameterType="String" resultType="String">
        select 
        KWORDID
        from 
        <include refid="tableName"></include>
        where PARENTID=#{PARENTID}
        order by KWORDID desc
        limit 0,1
    </select>
jsp中代码
    function validateKwordId(str){
            var parentid=$("#PARENTID").val()
            var result=false
            $.ajax({
                url:'kwords/validate',
                data:{PARENTID:parentid,KWORDID:str},
                async:false,
                dataType:'json',
                type:'post',
                success:function(resp){
                    if(resp.msg=='true'){
                        result=true
                    }
                }
            });
            return result;
        }
        function validateKwordName(str){
            var parentid=$("#PARENTID").val()
            var result=false
            $.ajax({
                url:'kwords/validate',
                data:{PARENTID:parentid,KWORDNAME:str},
                async:false,
                dataType:'json',
                type:'post',
                success:function(resp){
                    if(resp.msg=='true'){
                        result=true
                    }
                }
            });
            return result;
        }


        function changeParentid(){
            var pid=$("#PARENTID").val()
            $.ajax( {  
                 type : "POST",  
                 url : "kwords/findkwordid",  
                 data : "parentid=" + pid,  
                 success : function(data) {  
                    $("#KWORDID").val(data.nextKwordId);  
                    if(validateKwordName($("#KWORDNAME").val())){
                        $("#KWORDNAME").tips({
                            side:3,
                            msg:'主题名称重复，请更换',
                            bg:'#AE81FF',
                            time:2
                        });
                        $("#KWORDNAME").focus();
                    }
                 },
                 error : function() {  
                    $("#KWORDID").tips({
                        side:3,
                        msg:'主题代码变更失败',
                        bg:'#AE81FF',
                        time:2
                    });
                    $("#KWORDID").focus();  
                 }  
                });  
        }

Answer 1

同样条件下如果数据表中会有可能出现多条记录，那么可将返回结果改成list集合类型，获取到list结果后然后在做相关逻辑处理