CASE WHEN 语句中的多个条件答案

【问题标题】：Multiple conditions in CASE WHEN statementCASE WHEN 语句中的多个条件
【发布时间】：2022-08-17 20:57:55
【问题描述】：

我正在使用 SQL (Amazon Redshift) 处理招聘数据，其中每个申请人都有多个来源，我将这些数据分成不同的列，称为 source_1、source_2 和 source_3，以及 number_of_sources 列以记录该申请人有多少来源有。我们希望每个申请人只有一个来源，并且在如何选择哪个来源时要遵循一定的规则，我正在尝试编写一个 CASE WHEN 语句来实现这一点。我目前遇到错误，但我不明白为什么。

我的代码是：

CASE WHEN number_of_sources = 1
THEN source_1
  ELSE WHEN number_of_sources = 2
   and source_1 in (\'Email Applicant\', \'Job site\', \'Added manually\') THEN source_2
  ELSE WHEN number_of_sources = 2
   and source_2 in (\'Email Applicant\', \'Job site\', \'Added manually\') THEN source_1
  ELSE WHEN number_of_sources = 3
   and source_1 in (\'Email Applicant\', \'Job site\', \'Added manually\') 
   and source_2 in (\'Email Applicant\', \'Job site\', \'Added manually\')  THEN source_3
  ELSE WHEN number_of_sources = 3
   and source_1 in (\'Email Applicant\', \'Job site\', \'Added manually\') 
   and source_3 in (\'Email Applicant\', \'Job site\', \'Added manually\')  THEN source_2
  ELSE WHEN number_of_sources = 3
   and source_3 in (\'Email Applicant\', \'Job site\', \'Added manually\') 
   and source_2 in (\'Email Applicant\', \'Job site\', \'Added manually\')  THEN source_1
    ELSE \'Blank\'    END                                                                             as source_final
from staging.candidates_by_source

希望这是有道理的，任何建议将不胜感激！非常感谢

在CASE 子句中，您只需要ELSE 作为最后一个默认值。将您的 ELSE WHENs 更改为 WHENs。
@O.Jones 哦，天哪，我太慢了，非常感谢，仍然掌握 SQL！

标签： sql amazon-redshift case

【解决方案1】：

删除除最后一个以外的所有其他内容

CASE WHEN number_of_sources = 1
THEN source_1
   WHEN number_of_sources = 2
   and source_1 in ('Email Applicant', 'Job site', 'Added manually') 
 THEN source_2
  WHEN number_of_sources = 2
   and source_2 in ('Email Applicant', 'Job site', 'Added manually') 
THEN source_1
  WHEN number_of_sources = 3
   and source_1 in ('Email Applicant', 'Job site', 'Added manually') 
   and source_2 in ('Email Applicant', 'Job site', 'Added manually') 
  THEN source_3
  WHEN number_of_sources = 3
   and source_1 in ('Email Applicant', 'Job site', 'Added manually') 
   and source_3 in ('Email Applicant', 'Job site', 'Added manually')
  THEN source_2
   WHEN number_of_sources = 3
   and source_3 in ('Email Applicant', 'Job site', 'Added manually') 
   and source_2 in ('Email Applicant', 'Job site', 'Added manually')
   THEN source_1
    ELSE 'Blank'    END                                                                               as source_final
from staging.candidates_by_source

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