depot-shared-tianjin/src/main/java/com/chinaitop/depot/grainSituationCard/mapper/GrainTemperatureMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.chinaitop.depot.grainSituationCard.mapper.GrainTemperatureMapper" >
  <select id="test" parameterType="java.lang.String" resultType="java.lang.String">
    select
        t_points
    from
        t_testdata
    where
    <if test="id != null">
      id = #{id}
    </if>
  </select>
</mapper>