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 0.单表+@Fetch 注解 + fetchFilter 方法

@Data
@ResultEntity(SysUser.class)
public class SysUserVo {

    private Integer id;

    private String userName;

    private String password;

    private Integer roleId;

    private LocalDateTime create_time;

    @Fetch(source = SysUser.class, property = "roleId", target = SysRole.class, targetProperty = "id")
    private List<SysRoleVo> sysRoles;

}

List<SysUserVO> list = QueryChain.of(sysUserMapper)
        .from(SysUser.class)
        .fetchFilter(SysUserVO::getRoles,where->where.eq(SysRole::getStatus,1))
        .returnType(SysUserVO.class)
        .list();

fetchFilter方法是对@Fetch注解的增强，没有特殊要求一般，可忽略

1. 单表查询

SysUser sysUser = QueryChain.of(sysUserMapper)
        .eq(SysUser::getId, 1)
        .eq(SysUser::getUserName,'admin')
        .get();

2.VO 映射

@Data
@ResultEntity(SysUser.class)
public class SysUserVo {

    private Integer id;

    private String userName;

    //字段名字不一样时
    @ResultEntityField(property = "password")
    private String pwd;

}

SysUserVO sysUserVO = QueryChain.of(sysUserMapper)
        .eq(SysUser::getId, 1)
        .eq(SysUser::getUserName,'admin')
        .returnType(SysUserVO.class)
        .list();

3. join 查询

@Data
@ResultEntity(SysUser.class)
public class SysUserVo {

    private Integer id;

    private String userName;

    //字段名字不一样时
    @ResultEntityField(property = "password")
    private String pwd;
    
    //映射一个对象 1对1
    @NestedResultEntity(target = SysRole.class)
    prviate SysRole sysRole;
    
    //映射多个对象 1对多
    @NestedResultEntity(target = SysRole.class)
    prviate List<SysRole> sysRoles;

}

List<SysUserRoleVO> list = QueryChain.of(sysUserMapper)
        .from(SysUser.class)
        .join(SysUser.class, SysRole.class)
        .returnType(SysUserRoleVO.class)
        .list();

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例如：

1 . 多表 join A 内嵌 B B 内嵌 C 都可以

2 . 不使用 join 使用 @Fetch 注解 + fetchFilter 方法实现 将 A JOIN B 变成 query A + query B

3 . 使用 @Paging 注解 实现你的 xml 自动分页

4 . 使用 SQL 模板，让你 ORM 更简单更容易扩展，再也不怕被框架限制了