mybatis中mysql，sql能查到，但是返回结果为0的问题

问题起因，多数据库支持的问题。

ORCALE下，selectFuzzyByParam方法中的sql，单独执行能找到之，方法返回值也有对应的对象。

<select id="selectFuzzyByParam" parameterType="map" resultType="com.***.***.***.***.SysProjectDO">
    <if test="queryValue != null">
      <bind name="pattern1" value="'%' + queryValue + '%'" />
    </if>
    SELECT * FROM
    (
    select ID, CODE, NVL(TABLE1.TEXT,TABLE2.NAME) as NAME , STATUS, CREATOR, CREATE_TIME,
    UPDATE_TIME,PROJECT_DESC AS "desc",PROJECT_TYPE AS "type" from TABLE2
    LEFT JOIN TABLE1 on TABLE2.ID = TABLE1.DATA_ID
    <if test="languageCode != null">
      and TABLE1.LANGUAGE_CODE = #{languageCode}
    </if>
    )
    <where>
      <if test="queryValue != null">
        and NAME like #{pattern1}
      </if>
      <if test="status != null">
        and STATUS = #{status}
      </if>
      <if test="type != null">
        and "type" = #{type}
      </if>
    </where>
  </select>

本以为将sql中的NVL函数，换成mysql的IFNULL就可以。但是，替换后，出现很怪异的问题。单独执行sql，能查到数据。但是selectFuzzyByParam返回的集合却是空的。这种原因，应该是其中的别名设置有问题，主要是type的问题，改成如下格式后，问题解决。原因，应该是别名的处理方式不同导致的问题。oracle采用的是""的方式，而mysql采用的是``的方式。

<select id="selectFuzzyByParam" parameterType="map" resultType="com.***.***.***.***.SysProjectDO">
    <if test="queryValue != null">
      <bind name="pattern1" value="'%' + queryValue + '%'" />
    </if>
    SELECT * FROM
    (
    SELECT ID as id, CODE AS code, IFNULL(TABLE1.TEXT, TABLE2.NAME) AS name,
    STATUS as status, CREATOR as creator, CREATE_TIME as createTime, UPDATE_TIME as updateTime,
    PROJECT_DESC AS `desc`, PROJECT_TYPE AS `type` from TABLE2
    LEFT JOIN TABLE1 on TABLE2.ID = TABLE1.DATA_ID
    <if test="languageCode != null">
      and TABLE1.LANGUAGE_CODE = #{languageCode}
    </if>
    ) as tmpTable
    <where>
      <if test="queryValue != null">
        and NAME like #{pattern1}
      </if>
      <if test="status != null">
        and STATUS = #{status}
      </if>
      <if test="type != null">
        and `type` = #{type}
      </if>
    </where>
  </select>

标签：TABLE2,TABLE1,NAME,mysql,能查,CODE,sql,type,ID
来源： https://blog.csdn.net/gaoshan12345678910/article/details/100742380