“ LIKE”和“ LIKE”之间有什么区别和“ =”在SQL中？ [英] What's the difference between "LIKE" and "=" in SQL?

问题描述

之间是否有任何区别：

SELECT * FROM users WHERE username="davyjones"

和

SELECT * FROM users WHERE username LIKE "davyjones"

为此，

我主要是桌面应用程序开发人员）

(I think I've bungled up the syntax... pardon me for that,
I'm mostly a desktop app development guy)

推荐答案

按照SQL标准，区别在于对CHAR列中尾随空格的处理。示例：

As per SQL standard, the difference is treatment of trailing whitespace in CHAR columns. Example:

create table t1 ( c10 char(10) );
insert into t1 values ('davyjones');

select * from t1 where c10 = 'davyjones';
-- yields 1 row

select * from t1 where c10 like 'davyjones';
-- yields 0 rows

当然，假设您在符合标准的环境下运行DBMS。顺便说一句，这是CHAR和VARCHAR之间的主要区别之一。

Of course, assuming you run this on a standard-compliant DBMS. BTW, this is one the main differences between CHARs and VARCHARs.

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