本文介绍了带有 CONCAT 条件的 MySQL 选择的处理方法，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
我正在尝试在我的脑海中编译这个.. 我有一个包含名字和姓氏字段的表我有一个字符串，比如Bob Jones"或Bob Michael Jones"等等.
I'm trying to compile this in my mind.. i have a table with firstname and lastname fields and i have a string like "Bob Jones" or "Bob Michael Jones" and several others.
问题是，例如，我有Bob 的名字，和迈克尔·琼斯的姓
the thing is, i have for example Bob in firstname, and Michael Jones in lastname
所以我正在尝试
SELECT neededfield, CONCAT(firstname, ' ', lastname) as firstlast
FROM users
WHERE firstlast = "Bob Michael Jones"
但它说未知列firstlast"..有人可以帮忙吗?
but it says unknown column "firstlast".. can anyone help please ?
推荐答案
您提供的别名用于查询的输出 - 它们在查询本身中不可用.
The aliases you give are for the output of the query - they are not available within the query itself.
您可以重复表达式:
SELECT neededfield, CONCAT(firstname, ' ', lastname) as firstlast
FROM users
WHERE CONCAT(firstname, ' ', lastname) = "Bob Michael Jones"
或包装查询
SELECT * FROM (
SELECT neededfield, CONCAT(firstname, ' ', lastname) as firstlast
FROM users) base
WHERE firstLast = "Bob Michael Jones"
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