對表主鍵中沒有的值進行SQL連接

Question

我需要獲取未分配給用戶的批次ID。 我有以下選擇語句：

SELECT batch.id 
FROM batch 
WHERE (SELECT batch.id 
       FROM batch 
       JOIN user 
       WHERE batch.id = user.batch_id) "+ "!= batch.id 
  AND submitted = 0 
  AND batch.project_id = ?

除未將batch_id分配給用戶外，其他方法均有效。 我試過不只是將另一列添加到批處理中，但這需要很多工作。 有一個更好的方法嗎？ 我不在乎優化，我只需要工作即可。

CREATE TABLE batch
(
    id integer not null primary key autoincrement,
    filepath varchar(255) not null,
    project_id integer not null,
    submitted boolean not null
);

CREATE TABLE user
(
    id integer not null primary key autoincrement,
    first_name varchar(255) not null,
    last_name varchar(255) not null,
    user_name varchar(255) not null,
    password varchar(255) not null,
    num_records integer not null,
    email varchar(255) not null,
    batch_id integer not null
);

Answer 1

SELECT b.id
FROM batch b
LEFT JOIN user u ON u.batch_id = b.id
WHERE u.id IS NULL
  AND b.submitted = 0
  AND b.project_id = ?

Answer 2

這是一種經典的查詢類型，可以用兩種方式編寫

select batch.id
from batch
left join user on user.batch_id = batch.id
where user.id is null
and batch.submitted = 0 
and batch.project_id = ?

要么

select batch.id
from batch
where not exists (select 1 from user
where user.batch_id = batch.id)
and batch.submitted = 0 
and batch.project_id = ?