本文介绍了Case when then，但在 when 和 before then 内有 AND 条件的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
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
这篇关于Case when then，但在 when 和 before then 内有 AND 条件的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！
本站部分内容来源互联网,如果有图片或者内容侵犯您的权益请联系我们删除！