使用mybatis-plus能够节省很多sql代码的书写，也能使sql变得更加灵活，在对于比较复杂或者多表操作时，使用basemapper的sql方法不太能达到业务逻辑的需求，需要自定义sql，但是也要保证sql的灵活性。
最近在写业务的时候遇到一些坑，现在把遇到的相关问题和解决方案分享一下：
方法添加参数： @Param(Constants.WRAPPER)
IPageMethod(IPage
在mapper文件中对应位置添加 ${ew.customSqlSegment}
测试使用：
QueryWrapper queryWrapper = new QueryWrapper<>();
queryWrapper.eq("is_deleted", 0);
queryWrapper.eq("cultivation_type", "种鱼");
cultivationSpeciesMapper.speciesfishList(Condition.getPage(query), queryWrapper);
控制台打印的sql：
Execute SQL : select fc.id, fc.area_id, fc.father_count, fc.mother_count, fc.create_user , fc.create_time, fs.father_no, fs.mother_no, fs.average_weight, fs.species_img , fc.mother_count + fc.father_count as total from fd_cultivation fc left join fd_cultivation_species fs on fc.id = fs.cultivation_id where father_no = '1' and area_id = '2' and average_weight >= '4' and is_deleted = 0 and cultivation_type = '种鱼' limit 2, 22.UpdateWrapper操作
在mapper文件中修改和添加 ${ew.sqlSet}
update fd_cultivation as fc LEFT JOIN fd_cultivation_species as fs on fc.id = fs.cultivation_id set ${ew.sqlSet} where fc.id = #{id}
在方法中添加 @Param(“ew”)
int updateSpeciesFish(@Param("ew") UpdateWrapper query, Long id);
使用：
UpdateWrapper updateWrapper = new UpdateWrapper<>(); updateWrapper.set(ChangeStr(field.getName()), field.get(fishUpdateVo)); cultivationSpeciesMapper.updateSpeciesFish(updateWrapper, fishUpdateVo.getId());
控制台打印的sql：
Execute SQL : update fd_cultivation fc left join fd_cultivation_species fs on fc.id = fs.cultivation_id set area_id = 2, father_no = 1, mother_no = 2, father_count = 51, mother_count = 55, average_weight = 4.0, species_img = 'asdasjkld' where fc.id = 1552553355042705410
