1.首先要明白返回list 时 ,xml 中 resultType 的配置
1. 返回的为 List<String> 类型, resultType= ""
2. 返回的为 List<Vo>类型, resultType= ""
2. 返回为实体List<VO>时,如果实体的属性值都为null,也会报这个错,本人刚好遇到。
<select resultType= "">
SELECT DISTINCT as faId, as faName
FROM a
WHERE is not null
and is not null
<if test="vueIds != null and () > 0">
and IN
<foreach collection="vueIds" item="vueId" open="(" separator="," close=")">
#{vueId}
</foreach>
</if>
</select>
这个是修改后的sql, sql中没有 and is not null , 导致 筛选的2个字段都为null, 就会返回报错