mybatisplus之使用@Select解读
作者：强风吹拂str
这篇文章主要介绍了mybatisplus之使用@Select解读，具有很好的参考价值，希望对大家有所帮助。如有错误或未考虑完全的地方，望不吝赐教
mybatisplus使用@Select
在自己的mapper文件里面 比如我这个是ckDao.java文件，写个方法，然后就可以用 @Autowired 注册这个mapper，就会去执行sql语句
@Select("SELECT DISTINCT name FROM `ck` where company = '顺网' and deleted = 1")
List<CkEntity> listCompany();
@Select("SELECT count(*) FROM `ck` where company = '顺网' and deleted = 1" + " and name like '%${name}%'")
String countCompanyData(@Param("name") String name);实现方法
@Override
public XXX listCompanyData() {
List<CkEntity> ckEntities = ckDao.listCompany();
return XXX;
}mybatisplus @Select注解参数判空及SQL拼接
场景
在@Select注解使用中，自定义sql时，会存在一个或多个查询条件的情况，这样在注解形式sql里，插入参数需要进行判空
实例
@Select({"<script>"+
"SELECT DISTINCT "+
"a.monitor_id monitorId," +
"a.monitor_name monitorName," +
"a.target," +
"a.priority,"+
"a.gmt_create gmtCreate " +
"FROM "+
"alert a,"+
"( SELECT monitor_id, max( gmt_create ) gmt_update FROM alert GROUP BY monitor-id ) b " +
"WHERE " +
"a.monitor_id = b.monitor_id "+
"AND a.gmt_create = b.gmt_update " +
"AND DATEDIFF(gmt_create,NOW())=0 "+
"<when test='times!=null'>" +
"AND times = #{times}"+
"</when>"+
"<when test='monitorName!=null'" +
"AND monitor_name like concat('%',#(monitorName},'%')"
"</when>"+
"<when test='priority!=null'" +
"AND priority = #{priority}"+
"</when>"+
"</script>"})
List<IndicateDetail> getIndicatorList(@Param("monitorName")String monitor_name,@Param("times")String times,@Param("priority")String priority);用script标签包围，然后像xml语法写
条件匹配 =用 #{}包装传进来的参数，如果是模糊查询，需要使用函数concat拼接%字符串
总结
以上为个人经验，希望能给大家一个参考，也希望大家多多支持脚本之家。