联表查询

内联查询

public class Demo {
    @Autowired
    private SysUserMapper sysUserMapper;

    public void page() {
        Pager<SysUser> pager= QueryChain.of(sysUserMapper)
                .join(SysUser::getRoleId, SysRole::getId)
                .like(SysUser::getUserName,"abc")
                .paging(Pager.of(1));
    }
}

左联查询

左联查询 适合1对1情况，如果不是，则分页时需要关闭框架优化：Pager.of(1).setOptimize(false)

public class Demo {
    @Autowired
    private SysUserMapper sysUserMapper;

    public void page() {
        Pager<SysUser> pager= QueryChain.of(sysUserMapper)
                .leftJoin(SysUser::getRoleId, SysRole::getId)
                .like(SysUser::getUserName,"abc")
                .paging(Pager.of(1));
    }
}

右联查询

public class Demo {
    @Autowired
    private SysUserMapper sysUserMapper;

    public void page() {
        Pager<SysUser> pager= QueryChain.of(sysUserMapper)
                .join(JoinMode.RIGHT, SysUser::getRoleId, SysRole::getId)
                .like(SysUser::getUserName,"abc")
                .paging(Pager.of(1));
    }
}

全连接查询

public class Demo {
    @Autowired
    private SysUserMapper sysUserMapper;

    public void page() {
        Pager<SysUser> pager= QueryChain.of(sysUserMapper)
                .join(JoinMode.FULL, SysUser::getRoleId, SysRole::getId)
                .like(SysUser::getUserName,"abc")
                .paging(Pager.of(1));
    }
}

CROSS JOIN 连接查询

public class Demo {
    @Autowired
    private SysUserMapper sysUserMapper;

    public void page() {
        Pager<SysUser> pager= QueryChain.of(sysUserMapper)
                .crossJoin(SysRole.class)
                .like(SysUser::getUserName,"abc")
                .paging(Pager.of(1));
    }
}

联表查询-ON条件：多个条件，怎么写？

public class Demo {
    @Autowired
    private SysUserMapper sysUserMapper;

    public void page() {
        Pager<SysUser> pager= QueryChain.of(sysUserMapper)
                .join(JoinMode.RIGHT, SysUser::getRoleId, SysRole::getId, on ->on.eq(SysRole::getId,1))
                .like(SysUser::getUserName,"abc")
                .paging(Pager.of(1));
    }
}

其他join（leftJoin,rightJoin,innerJoin）方法都有，以此类推

join子查询 ？

SubQuery subQuery=SubQuery.create("sub")
    .select(SysRole.class)
    .from(SysRole.class)
    .eq(SysRole::getId,1);

List<SysUser> list=QueryChain.of(sysUserMapper)
    .select(SysUser.class)
    .from(SysUser.class)
    .innerJoin(SysUser.class,subQuery,on->on.eq(SysUser::getRole_id,subQuery.$outerField(SysRole::getId)))
    .list();

更多复杂的join查询 前往查看