MySQL 当一个字段不等于另一个字段时，带有条件的 SQL 查询
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/11241958/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
SQL query with condition when one field not equal to another
提问by Vitaly Lebedev
Let's say we have fields: id | content | updateTime | creationTime
假设我们有字段： id | 内容 | 更新时间 | 创建时间
When insertion done both updateTime and creationTime get filled with current time. On update only updateTime field get changed. When I need to find all data created on '2012-06-28' I simply use:
插入完成后， updateTime 和 creationTime 都会填充当前时间。更新时只有 updateTime 字段会发生变化。当我需要查找在“2012-06-28”上创建的所有数据时，我只需使用：
SELECT id, content FROM tbl WHERE creationTime LIKE '2012-06-28%'`
But to get all data that was updated excluding created data I need to use something like this:
但是要获取不包括创建的数据的所有更新数据，我需要使用以下内容：
SELECT id, content FROM tbl WHERE creationTime LIKE '2012-06-28%' AND creationTime != updateTime
This can't work, obviously. Though I could find all updated data by comparing values of two 'time' collumns inside php, I'd still love to do it inside query.
这显然行不通。虽然我可以通过比较 php 中两个“时间”列的值来找到所有更新的数据，但我仍然喜欢在查询中进行。
UPD: Well, it turns out that I was absolutely unaware that sql allows not only compare value of a field with a given variable, number... but also it can compare value of one field with another.
UPD：好吧，事实证明我完全不知道 sql 不仅允许将字段的值与给定的变量、数字进行比较……而且它还可以将一个字段的值与另一个进行比较。
回答by DonCallisto
Use <>instead !=(that isn't compatible with some DMBS)
使用<>替代!=（即不兼容一些DMBS）
So
所以
SELECT id, content
FROM tbl
WHERE creationTime LIKE '2012-06-28%' AND creationTime <> updateTime
If you want some documentation you can find here
如果你想要一些文档，你可以在这里找到
However, your query have to work properly with !=
但是，您的查询必须与 !=
回答by bluehallu
Your query is correct (on mySQL1), don't know why would you think otherwise
您的查询是正确的（在 mySQL1 上），不知道您为什么会这么想
1 <>is the SQL operator for not equal. Some implementations of it (PostgreSQL or MySQL for instance), however, accept !=too. It is a good practice to always use <>to avoid problems if you ever use your code on a different database.
1<>是不等于的 SQL 运算符。但是，它的一些实现（例如 PostgreSQL 或 MySQL）!=也接受。<>如果您曾经在不同的数据库上使用您的代码，那么始终使用它是一种很好的做法，以避免出现问题。
回答by Shaikh Farooque
Only change the not operator from !=to <>
仅将 not 运算符从 更改!=为<>
SELECT id, content FROM tbl WHERE creationTime LIKE '2012-06-28%' AND creationTime <> updateTime
