仅返回基于多连接中的一列的最小记录

Posted 2023-03-17

【中文标题】仅返回基于多连接中的一列的最小记录

【英文标题】：Return only minimum record based on one column in a multiple join

【发布时间】：2021-10-06 22:36:57

【问题描述】：

我有一个包含几个连接的查询，它返回两条记录，我只希望它为每个 acme_id（最小 acme_client_id）返回一条记录。 （或者最小的 acme_client.client_id，我不在乎。）我尝试了很多不同的方法，但我无法让它工作。

SELECT
    acme_client_id,
    acme_client.client_id,
    acme_id
FROM
    acme_client WITH (NOLOCK)
    LEFT JOIN client WITH (NOLOCK) ON acme_client.client_id = client.client_id
    LEFT JOIN acme_client_information WITH (NOLOCK) ON client.acme_client_information_id = acme_client_information.acme_client_information_id
WHERE
    acme_client.acme_decisionmaker_ind = 1
    and acme_client.acme_current_owner_ind = 0
    AND (
        acme_client.participant_start_date IS NULL
        OR acme_client.participant_start_date < GETDATE()
    )
    AND (
        acme_client.participant_end_date IS NULL
        OR acme_client.participant_end_date > GETDATE()
    )
    AND (
        acme_client.acme_client_id IN (
            SELECT
                acme_cooperating_entity_client.acme_client_id
            FROM
                acme_cooperating_entity_client WITH (NOLOCK)
        )
    )
)

【问题讨论】：

签出row_number()

停止使用nolock 溅出你的代码

提供样本数据和所需的输出

【参考方案1】：

可能是这样的

SELECT min(ac.acme_client_id) min_ac_id,
       min(ac.client_id) min_c_id,
       ac.acme_id
FROM acme_client ac
     join acme_cooperating_entity_client acec on ac.acme_client_id=acec.acme_client_id
     LEFT JOIN client c ON ac.client_id = c.client_id
     LEFT JOIN acme_client_information aci ON c.acme_client_information_id = aci.acme_client_information_id
WHERE ac.acme_decisionmaker_ind = 1 
      and ac.acme_current_owner_ind = 0
      AND (ac.participant_start_date IS NULL
           OR ac.participant_start_date < GETDATE())
      AND (ac.participant_end_date IS NULL
           OR ac.participant_end_date > GETDATE())
group by ac.acme_id;