在 SQL 查询中使用固定列表作为随机值

Question

我有一张表，我想在其中生成测试数据：

INSERT into onboarding_tasks (business_name, created_at, status)
SELECT
    'Business name ' || id AS business_name,
    (NOW() + (random() * (NOW() + '90 days' - NOW())) + '30 days') AS created_at,
    /* here I can have values NEW, IN_PROGRESS, COMPLETED */ AS status,    
FROM generate_series(1,25) as g(id);

您知道我如何在 SQL 查询中实现逻辑以从固定选项生成随机值吗？

Answer 1

您可以将CASE 与RANDOM() 函数结合使用来实现此目的。

例如：

SELECT
    'Business name ' || id AS business_name,
    (NOW() + (random() * (NOW() + '90 days' - NOW())) + '30 days') AS created_at,
    case when random() < 0.3333 then 'NEW'
         when random() < 0.5 then 'IN_PROGESS'
         else 'COMPLETED'
    end AS status
FROM generate_series(1,10) as g(id);

结果：

 business_name     created_at                     status     
 ----------------- ------------------------------ ---------- 
 Business name 1   2021-12-03 07:37:08.519843+00  NEW        
 Business name 2   2022-01-22 19:14:10.085483+00  COMPLETED  
 Business name 3   2021-11-23 16:47:39.207064+00  COMPLETED  
 Business name 4   2022-01-26 13:08:33.643398+00  NEW        
 Business name 5   2021-12-05 03:26:44.730359+00  COMPLETED  
 Business name 6   2022-02-07 07:15:05.470689+00  COMPLETED  
 Business name 7   2022-01-13 05:00:15.326175+00  COMPLETED  
 Business name 8   2022-02-08 02:43:43.123768+00  IN_PROGESS 
 Business name 9   2021-11-17 06:06:40.14872+00   NEW        
 Business name 10  2021-12-19 07:59:55.786655+00  NEW        

请参阅db<>fiddle 的运行示例。