mysql - 使用 Case 语句更新表

Question

UPDATE crm_accounts 
SET 
    reg = "Sim" 
WHERE age >= 17 
AND age <= 35 
AND balance > 0.00
AND type = "Júnior";


UPDATE crm_accounts 
SET 
    reg = "Não" 
WHERE age >= 17 
AND age <= 35 
AND balance = 0.00
AND type = "Júnior";


UPDATE crm_accounts 
SET 
    type = "Efetivo"
WHERE age >= 17
AND age <= 35 
AND type = "Júnior";

该语句用于此目的，但我想简化并合并到一个案例语句中。有什么帮助吗？谢谢。

Answer 1

看起来你想要这样的东西:

 UPDATE crm_accounts a
    SET a.reg 
      = CASE
          WHEN a.balance > 0.00 THEN 'Sim'
          WHEN a.balance = 0.00 THEN 'Não'
          ELSE a.reg
        END
      , a.type = 'Efetivo'
  WHERE a.age >= 17
    AND a.age <= 35
    AND a.type = 'Júnior'

---

每当我写这样的更新语句时，我总是先测试 SELECT 语句中的表达式和谓词，然后验证结果。在将其转换为 UPDATE 语句之前，我确保一切都按我需要的方式工作。

 SELECT a.age >= 17
      , a.type
      , a.reg AS old_reg
      , CASE
          WHEN a.balance > 0.00 THEN 'Sim'
          WHEN a.balance = 0.00 THEN 'Não'
          ELSE a.reg
        END AS new_reg
   FROM crm_accounts a
  WHERE a.age >= 17
    AND a.age <= 35
    AND a.type = 'Júnior'