mybatis 多表关联mapper文件写法

两张表SystemParam（系统参数表） Suit （主题）
SystemParam 与 Suit 是多对一
Suit 的higerSuit字段是Suit 的父及主题id 是多对一，需要自连接查询，因为重名所以父表sql字段加别名

mapper方法

Systemparam selectJoinSuit(String strparamcode);

Po类

public class Systemparam {
    //ManyToOne "主题"
    private Suit suitobj;
    private String strparamcode;
    private String strenable;
    private String strparamname;
    //suit表主键
    private String suit;
    private String strparamvalue;
｝

 

public class Suit {
    //ManyToOne
    private Suit suit;
    //主键
    private String strsuitcode;
    private String strsuitname;
    //父级id
    private String higersuit;
｝

 

resultMap的写法


  
  
  
  

resultMap 使用extends 继承上级map

  


  
    
    
    
    
      
      
      
    
  

select写法

  select
  systempara0_.*,
  suit1_.*,
  suit2_.strSuitCode pstrSuitCode,
  suit2_.strSuitName pstrSuitName,
  suit2_.higerSuit phigerSuit
  from SystemParam systempara0_
  LEFT OUTER JOIN
  Suit suit1_
  ON systempara0_.suit=suit1_.strSuitCode
  LEFT OUTER JOIN
  Suit suit2_
  ON suit1_.higerSuit=suit2_.strSuitCode
  WHERE
  systempara0_.strParamCode=#{strparamcode,jdbcType=VARCHAR}