Question

SELECT * FROM company_disposition WHERE company_id = $1 AND campaign_uuid = 'null' OR campaign_uuid != $2

这是我的postgres请求..我不想获得所有值which company_id = $1 AND campaign_uuid = 'null' OR campaign_uuid != $2 ..如何制作它？我看到的请求无效//

 {
      "company_id": "be1b5ee1-51e7-422b-b469-592dbd62bec9",
      "disposition": "string",
      "disposition_uuid": "8f66c72a-9a68-440a-bd7f-3a0f49ef4973",
      "disposition_order": 2323,
      "campaign_uuid": "fd80a1fa-947d-4b09-a755-cee5951b6c85"
    },
    {
      "company_id": "be1b5ee1-51e7-422b-b469-592dbd62bec9",
      "disposition": "strinsdsdg",
      "disposition_uuid": "4c8e9601-1894-4e69-b22c-f2b83d9d80bb",
      "disposition_order": 2323,
      "campaign_uuid": null
    }

我想得到这个：

 {
      "company_id": "be1b5ee1-51e7-422b-b469-592dbd62bec9",
      "disposition": "strinsdsdg",
      "disposition_uuid": "4c8e9601-1894-4e69-b22c-f2b83d9d80bb",
      "disposition_order": 2323,
      "campaign_uuid": null
    }

"campaign_uuid" - 可以是值或null

Answer 1

您的查询有两个问题（如果我正确阅读）：

使用=运算符与NULL进行比较。

SQL对比较运算符使用三值逻辑，因此将NULL（= unknown）与任何事物进行比较既不是TRUE也不是FALSE，而是NULL。

这意味着条件something = NULL永远不会TRUE（它始终为NULL）。

您必须使用IS NULL运算符来测试值是否为NULL。
您忘记AND的优先级高于OR，因此您必须使用括号。

我认为你的意思是：

SELECT * FROM company_disposition
WHERE company_id = $1
  AND (campaign_uuid IS NULL OR campaign_uuid <> $2);

如果您从未提供$ 2的NULL值，则更简单的方法是

SELECT * FROM company_disposition
WHERE company_id = $1
  AND campaign_uuid IS DISTINCT FROM $2;

Answer 2

SELECT * FROM company_disposition WHERE company_id = $1 AND campaign_uuid is null OR campaign_uuid <> $2 AND company_id = $1

Answer 3

尝试：

SELECT * FROM company_disposition WHERE company_id = $1 AND (campaign_uuid is null OR campaign_uuid <> $2)

此查询可能会返回多行，所有行都包含company_id = $ 1和campaign_uuid！= $ 2，（条件campaign_uuid！= $ 2将包含campaign_uuid = null的行），如果您只想获取一行每个company_id，你需要使用＆＃34; DISTINCT＆＃34;

示例：

SELECT DISTINCT ON (company_id)
     company_id,
     disposition,
     disposition_uuid,
     disposition_order,
     campaign_uuid
FROM
   company_disposition
WHERE
   company_id = $1 AND
   (campaign_uuid is null OR campaign_uuid <> $2)
ORDER BY company_id

WHERE，AND .OR在一个请求中

3 个答案: