英文:
How to perform a LEFT JOIN in SOQL
问题
我有一个SQL查询，我想转换为SOQL。
我知道在SOQL中不支持LEFT JOIN。但我不知道如何在SOQL中编写这个查询。
我想要检查没有Decision__c的Cases。Case(Id)和Decision__c (Case__c)之间存在查找关系。
在SQL中，可以这样写：
Select Id
FROM Case
LEFT JOIN Decision__c D
on D.Case__c = Case.Id
WHERE Case__c IS NULL
我将所有的Cases (Case)和所有的Decisions (Decision__c)导出到Excel。通过VLOOKUP，我将Case与Decision连接起来。如果出现错误，则表示没有关联的Decision。
我在PowerQuery中导出了这些对象，并执行了左连接以合并两个查询。那些没有Decision的记录很容易被过滤掉（null值）。
所以我得到了没有Decision的Cases列表，但我想知道是否可以使用SOQL查询来获取这个列表，而不是这些额外的步骤。
英文:
I have a query in SQL that I want to convert to SOQL.
I know that a LEFT JOIN is not possible in SOQL. But I don't how to write this in SOQL.
I want to check Cases without Decision__c. There is a Lookup relation between Case(Id) and Decision__c (Case__c).
That would be in SQL:
Select Id
FROM Case
LEFT JOIN Decision__c D
on D.Case__c = Case.Id
WHERE Case__c IS NULL
I exported all Cases (Case) and all Decisions (Decision__c) to Excel. With a VLOOKLUP I connected the Case with the decision. An error = no linked decision.
I exported the objects in PowerQuery and performed a left join to merge the two queries. Those with no decision where easily filtered (null value).
So I got my list of Cases without Decision, but I want to know if I can get this list with a SOQL query, instead of these extra steps.
答案1
得分: 0
简而言之，您必须从没有 Decision__c 的情况下，选择案例，查询应该如下所示：
SELECT Id FROM Case WHERE Id NOT IN(SELECT Case__c FROM Decision__c)
虽然在 Salesforce 中我们不使用 JOINs，但可以使用几个“子查询”来帮助筛选记录。
英文:
<p>To simply put it, you must, literally, select cases without Decision__c, the query should look like this:</p>
<p>SELECT Id FROM Case WHERE Id NOT IN(SELECT Case__c FROM Decision__c)</p>
<p>Although we don't JOINs in Salesforce we can use several "subqueries" to help filter records.</p>
refer to the following link:
https://developer.salesforce.com/docs/atlas.en-us.soql_sosl.meta/soql_sosl/sforce_api_calls_soql_select.htm
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