實體類的參數(shù)

@JoinEntity(joinEntityAlias = T_DeviceMoxing_AlarmRule,...)的作用

課室類

@Entity

public class Classroom {

private int id;

private String name;

...

}

老師類

注意其中的靜態(tài)str

@Entity

public class Teacher {

public static final String T_Classroom = "T_Classroom";

private int id;

private String name;

@JoinEntity(name = "id",joinEntityClass = Classroom.class,joinEntityAlias =T_Classroom)

private int classroomId;

@Transient

@FieldPath(name = "name",joinEntityClass = Classroom.class,joinEntityAlias = T_DeviceMoxing_AlarmRule)

private String classroomIdName;

...

}

查詢實體

注意其中的,joinEntityAlias

@JoinEntity(mainEnityClass = Teacher.class,joinEntityClass = Classroom.class, mainFiledName = "classroomId",name = "id",fieldType = Integer.class)

public class QueryBean {

//根據(jù)課室名模糊查詢

@Like

@FieldPath(joinEntityClass = Classroom.class,name = "name",joinEntityAlias = Teacher.T_Classroom)

private String classroomIdName;

//用到的包

import swallow.framework.jpaquery.repository.annotations.FieldPath;

import swallow.framework.jpaquery.repository.annotations.JoinEntity;

import swallow.framework.jpaquery.repository.annotations.Like;

//根據(jù)課室名稱模糊查詢配備的教師數(shù)量

SELECT count

FROM

Teacher teacher

LEFT JOIN Classroom T_Classroom

WITH T_Classroom .Id = teacher.classroom_id

WHERE T_Classroom.name LIKE ?

如果在查詢實體中的去掉

joinEntityAlias = Teacher.T_Classroom

的話，那么生成的sql就會報錯，找不到Classroom.name字段

SELECT count

FROM

Teacher teacher

LEFT JOIN Classroom T_Classroom

WITH T_Classroom .Id = teacher.classroom_id

WHERE Classroom.name LIKE ?

剛開始使用時覺得joinEntityAlias沒什么用就省略了，覺得很多余，后來才知道原來是這么用的。而且不加會導(dǎo)致級聯(lián)查詢也會有問題，只要會debug這些都好解決

總結(jié)

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