mybatis and,or复合查询操作

要查询的sql:

select * from user where name = ? and (age=? or city=?)；

方法1：不使用example查询

直接在usermapper.xml中修改sql

方法2：使用example查询

sql可转换成

select * from user where (name = ? and age=?) or (name=? and city=?)；

然后使用example查询

userexample example=new userexample();
example.or().oragelike("%"+searchparam+"%").andnameequalto(username);
example.or().orcitylike("%"+searchparam+"%").andnameequalto(username);

补充知识：mysql/mybatis多个and和or混用注意事项

mysql中and的优先级高于or，所以在查询时，会优先执行and条件，除非使用（）来将一个and和or括起来，这样才能使得or得以按照语句的顺序执行。

如下图所示：

java测试代码

@test
 public void testmutil(){
  species species = new species();
  arraylist<string> arraylist = new arraylist<string>();
  arraylist.add("长喙蚤");
  arraylist.add("尤氏");
  list<species> queryspecieseslistbymutilcondition = this.speciesmapper.queryspecieseslistbymutilcondition(arraylist, species.getenglishname(), species.gethost(), species.getposition(), species.getlocation(), species.getphylum(), species.getclassname(), species.getorder(), species.getfamily(), species.getjenus());
  
  for (species s : queryspecieseslistbymutilcondition) {
   system.out.println(s);
  }
  system.out.println(queryspecieseslistbymutilcondition.size());
  
 }

mapper文件中没有使用（）放在语句中执行情况

<select id="queryspecieseslistbymutilcondition" resulttype="species">
 select * from t_json_species
 <where>
 <if test="englisname != null and englisname != ''">and englishname like concat('%',#{englishname},'%') or samename like concat('%',#{englishname},'%')</if>
 <if test="host != null and host != ''">and host like concat('%',#{host},'%')</if>
 <if test="position != null and position != ''">and position like concat('%',#{position},'%')</if>
 <if test="location != null and location != ''">and location like concat('%',#{location},'%')</if>
 <if test="phylumname != null and phylumname != ''">and phylumname = #{phylumname}</if>
 <if test="classname != null and classname != ''">and classname = #{classname}</if>
 <if test="ordername != null and ordername != ''">and ordername = #{ordername}</if>
 <if test="familyname != null and familyname != ''">and familyname = #{familyname}</if>
 <if test="jenusname != null and jenusname != ''">and jenusname = #{jenusname}</if>
 <if test="namelist != null and namelist != ''">
 <foreach collection="namelist" item="name" >and name like concat('%',#{name},'%') or samename like concat('%',#{name},'%')</foreach>
 </if>
 </where>
 
 </select>

mapper文件中使用（）放在语句中执行情况

<select id="queryspecieseslistbymutilcondition" resulttype="species">
 select * from t_json_species
 <where>
 <if test="englisname != null and englisname != ''">and englishname like concat('%',#{englishname},'%') or samename like concat('%',#{englishname},'%')</if>
 <if test="host != null and host != ''">and host like concat('%',#{host},'%')</if>
 <if test="position != null and position != ''">and position like concat('%',#{position},'%')</if>
 <if test="location != null and location != ''">and location like concat('%',#{location},'%')</if>
 <if test="phylumname != null and phylumname != ''">and phylumname = #{phylumname}</if>
 <if test="classname != null and classname != ''">and classname = #{classname}</if>
 <if test="ordername != null and ordername != ''">and ordername = #{ordername}</if>
 <if test="familyname != null and familyname != ''">and familyname = #{familyname}</if>
 <if test="jenusname != null and jenusname != ''">and jenusname = #{jenusname}</if>
 <if test="namelist != null and namelist != ''">
 <foreach collection="namelist" item="name" >and (name like concat('%',#{name},'%') or samename like concat('%',#{name},'%'))</foreach>
 </if>
 </where>
 
 </select>

补充：

如果这里使用多个%来解决上述的含有多个or和and情况，那么所实现功能会有问题，因为多个关键词有%来连接，会有一个次序问题。具体效果见下图

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