Case when then，但在 when 和 before then 内有 AND 条件

Case when then, but with AND condition inside when and before then(Case when then，但在 when 和 before then 内有 AND 条件)

问题描述

在下面的查询中，我想在 CASE 的 WHEN 和 THEN 之前添加一个 AND 条件，这可能吗?

In the below query I want to add an AND condition inside the CASE's WHEN and before THEN is that possible?

例如 WHEN 'r' AND table1.name="jones" THEN 'very high'

for example WHEN 'r' AND table1.name="jones" THEN 'very high'

SELECT table1.id, table1.name,
   CASE table1.event
     WHEN 'r' THEN 'very high'
     WHEN 't' THEN 'very low'
     ELSE (SELECT table2.risk FROM table2 WHERE table2.value <= table1.value
           ORDER BY table2.value DESC LIMIT 1)
   END AS risk
FROM table1
ORDER BY FIELD( table1.event, 'r', 'f', 't' ), table1.value DESC

推荐答案

你可以像这样重写你的语句来完成你想要的

You can rewrite your statement like this to accomplish what you want

SELECT table1.id, table1.name,
   CASE 
     WHEN table1.event = 'r' AND table1.name = 'jones' THEN 'very high'
     WHEN table1.event = 't' AND table1.name = 'smith' THEN 'very low'
     ELSE (SELECT table2.risk FROM table2 WHERE table2.value <= table1.value
           ORDER BY table2.value DESC LIMIT 1)
   END AS risk
FROM table1
ORDER BY FIELD( table1.event, 'r', 'f', 't' ), table1.value DESC

注意您需要删除CASE 语句之后的table1.event.此处的文档

notice that you need to remove table1.event after the CASE statement. documentation here

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