这是一个可以通过java代码凭借sql语句

🚀maven引入

<dependency>
    <groupId>io.github.pwxpwxtop</groupId>
    <artifactId>joinsql</artifactId>
    <version>1.0.0</version>
</dependency>

这是我创建的ScrollStuendt.java实体类

@Data
public class ScrollStudent {

    //学生id
    private String id;

    //学上姓名
    private String name;

    //学生年龄
    private Integer age;

    //学生班级id
    private String classId;

    //学校id
    private String scrollId;
}

mysql数据库表

CREATE TABLE `scroll_student` (
  `id` bigint NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `age` int DEFAULT NULL,
  `class_id` bigint DEFAULT NULL,
  `scroll_id` bigint DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

调用工具类Table.gen(Class cls)

Table table = Table.gen(ScrollStudent.class);
System.out.println(table.getSql());

打印如下：
select ss.id, ss.name, ss.age, ss.class_id, ss.scroll_id from scroll_student as ss where 1=1    

多个表查询

创建Scroll.java

@Data
public class Scroll {

    //学校id
    private String id;

    //学校名称
    private String name;

}

CREATE TABLE `scroll` (
  `id` bigint NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;

使用方法1

Table table1 = Table.gen(ScrollStudent.class);
Table table2 = Table.gen(Scroll.class);
System.out.println(
    table1.leftJoin(
        table2, "scroll_id", "id")
    .eq("name", "张三")
    .getSql()
);

打印结果：
select ss.id, ss.name, ss.age, ss.class_id, ss.scroll_id from scroll_student as ss left join scroll as s on ss.scroll_id = s.id where 1=1  and ss.name = '张三' 

项目待更新。。。