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> 来源：51CTO
作者：gaoshan12345678910
链接：https://blog.csdn.net/gaoshan12345678910/article/details/100742380