MyBatis实现SaveOrUpdate

例子

<insert id="saveOrUpdate" >
  <selectKey keyProperty="count" resultType="int" order="BEFORE">
    select count(*) from country where id = #{id}
  </selectKey>
  <if test="count > 0">
    update country 
    set countryname = #{countryname},countrycode = #{countrycode} 
    where id = #{id}
  </if>
  <if test="count==0">
    insert into country values(#{id},#{countryname},#{countrycode})
  </if>
</insert>

 

csdn上的代码，唯一必须注意的是 keyProperty="count" ，要在实体类dto里面有

<selectKey keyProperty="count" resultType="int" order="BEFORE">
    select count(*) from country where id = #{id}
  </selectKey>