Mybatis common summary

1. Parameter injection
1.1 uses the form of #{0}, #{1}, 0 represents the first parameter, 1 represents the second parameter
　public List queryList(String workerId, Integer topNum);

　
SELECT ID id, WORKER_ID workerId, UPDATE_DATE updateDate
　　　FROM USER_RECORDS t
　　　WHERE t.WORKER_ID = #{0}
　　LIMIT #{1}
　
1.2Map or encapsulated object, workerId is the key in the map; if it is an object, workerId For attributes in objects, this method is very commonly used
　　public Integer queryCountByWorkerId(Map queryParam);
　public Integer queryCountByWorkerId(@param(“workerId”)String workerId);　

　　SELECT COUNT(1)
　　FROM tableName F
　　WHERE F.WORKER_ID = #{workerId}　

2. Return
2.1 mapping
　

　

　　
　　
　　
　　
　
　
　　select ID,CREATE_DATE,WORKERID from tableName
　
　This way the query statement queries the fields directly It’s just a field in the database, just define the mapped column
2.2 Return the object directly　
　　select ID id,CREATE_DATE createDate,WORKERID workerId from tableName
　

　The field alias returned by the query here must correspond to the attributes in the returned object

3. Execute native sql
3.1sql parameters: 　public class ParamVo {

　　private String sql;　　　//getter setter omitted

　　}

3.2 interface:
　 /**
　 * @Function description: Create

　 * @param vo

　 * @return
　*/

　 public int excuteCreateSql(ParamVo vo);

　 /**
　 * @Function description: Query
　 * @param vo
　 * @return
　*/
public List
> excuteSelectSql(ParamVo vo);

3.3xml:
　

　　${sql}
　

　${}Do not compile sql and execute it directly. If you use #{sql}, an error may be reported

　

4.2 Quote
　　
　　 SELECT COUNT(1)
　　

　
　　

　　 SELECT ID id, WORKER_ID workerId, UPDATE_DATE updateDate,...