MySQL Case语句-where中的未知列

我的疑问有问题，怎么了

SELECT 
    CASE 
        WHEN cp_pessoa.score < 100 THEN 1 
        WHEN cp_pessoa.score < 300 THEN 2 
        WHEN cp_pessoa.score >= 300 THEN 3 
    END as id_ranking
FROM cp_pessoa 
    WHERE id_ranking IN (1,2);

我得到了这个错误：1054-where子句中的未知列“id_ranking”

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谢谢大家!

这是因为选择prepare result作为id\u排名，而不是调用WHERE

SELECT 
    CASE 
    WHEN cp_pessoa.score < 100 THEN 1 
    WHEN cp_pessoa.score < 300 THEN 2 
    WHEN cp_pessoa.score >= 300 THEN 3 
END as id_ranking
FROM cp_pessoa 
WHERE cp_pessoa.score < 300;

这就是它的工作原理：

FROM子句 WHERE子句 分组依据子句 有从句 SELECT子句 按条款订货

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您不能在where子句中使用别名，请尝试

SELECT 
CASE 
    WHEN cp_pessoa.score < 100 THEN 1 
    WHEN cp_pessoa.score < 300 THEN 2 
    WHEN cp_pessoa.score >= 300 THEN 3 
END as id_ranking
FROM cp_pessoa 
WHERE cp_pessoa.score < 300

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where中不允许使用别名。将查询更改为

SELECT * FROM 
(
SELECT 
    CASE 
        WHEN cp_pessoa.score < 100 THEN 1 
        WHEN cp_pessoa.score < 300 THEN 2 
        WHEN cp_pessoa.score >= 300 THEN 3 
    END as id_ranking
FROM cp_pessoa 
)a 
WHERE id_ranking IN (1,2)

或

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哪里看不到别名。没有其他方法来解析？工件id_ranking1,2是可变的。这是一个很好的标准方法，但你可以用许多其他方法得到一个结果。例如，您可以在WHERE子句中重复您的案例，或者选择到另一个表中，然后使用当前的子句2查询。但是你真的需要这个吗？你在任何地方都能工作，因为1，2和3总是<300@BaBL86：正确，正在修复

SELECT 
    CASE 
        WHEN cp_pessoa.score < 100 THEN 1 
        WHEN cp_pessoa.score < 300 THEN 2 
        WHEN cp_pessoa.score >= 300 THEN 3 
    END as id_ranking
FROM cp_pessoa 
WHERE 
  CASE 
        WHEN cp_pessoa.score < 100 THEN 1 
        WHEN cp_pessoa.score < 300 THEN 2 
        WHEN cp_pessoa.score >= 300 THEN 3 
    END IN (1,2)