spring data jpa 查询部分字段

 @Query("select new map(ah as ah,salq as sqlq,yg as yg,
             bg as bg,ay as ay) FROM Aj where ahdm=?1")
 Map<String,Object> findSomeByAhdm(String ahdm);

　　查询一些字段，得到的是key为 ah,salq,yg,bg,ay的map

　　

 @Query("select new map(ah,salq,yg,bg,ay) FROM Aj where ahdm=?1")
 Map<String,Object> findSomeByAhdm(String ahdm);

　　不加as别名，得到的map，key为index

还可以用原生sql查询https://www.cnblogs.com/coder-lichao/p/10732090.html