postgresql JOIN 具有多个条件

Question

我有两个 postgres 表：

worker_details_verification (verification_id BIGSERIAL, worker_id BIGINT, 
state TEXT, proofs TEXT[])
worker_details(worker_id BIGINT, name TEXT)

现在我想得到

    `verification_id, worker_id, proofs FROM` the table 
    `worker_details_verification`  

限制记录 `WHERE state = 'Initial'

现在除了上述三列之外，我worker_details还想要表中的名称列，其中worker_id可用于查询工人的姓名。

我尝试了以下查询，但没有成功。

SELECT a.verification_id, a.worker_id, a.state, a.proofs, b.Name FROM 
worker_details_verification a FULL OUTER JOIN worker_details b ON 
a.worker_id = b.worker_id AND a.state = 'Initial';

它返回甚至 a.state 都不是的记录'Initial'，并且还返回一些错误的记录，其中所有namefrom都与for列worker_detail一起返回。NULLworker_details_verification

Answer 1

在我看来，您需要的是左/右连接，而不是完全外连接，因为您正在从 Worker_Details_Verification 中查找数据，然后对其进行过滤，同时在适用的情况下获取 Worker_Details 。

我采取了这个：

SELECT a.verification_id, a.worker_id, a.state, a.proofs, b.Name 
FROM worker_details_verification a 
     FULL OUTER JOIN worker_details b ON a.worker_id = b.worker_id AND a.state = 'Initial';

并把它变成这样：

SELECT a.verification_id, a.worker_id, a.state, a.proofs, b.Name 
FROM worker_details_verification a 
     LEFT OUTER JOIN worker_details b ON a.worker_id = b.worker_id 
WHERE a.state = 'Initial';