我应该在使用字符串替换进行更新时添加WHERE子句(Should I add a WHERE clause when updating with string replacements)

 我想在整个列上执行字符串替换，将一个短语的所有实例更改为另一个： 
 
UPDATE `some_records`
SET `some_column` = REPLACE(`some_column`, 'foo', 'bar');
 
 由于许多行不包含字符串'foo'，因此它们不受此查询的影响，这很好; 我只关心包含它的行。 我的问题是，有没有理由添加一个WHERE子句来明确地定位将受影响的行？ 例如 
 
UPDATE `some_records`
SET `some_column` = REPLACE(`some_column`, 'foo', 'bar')
WHERE `some_column` LIKE '%foo%';
 
 据我所知，两个查询都有完全相同的效果。 第二版有什么优势吗？ 它是否提供更好的性能或任何其他好处？ 到目前为止，我还没有找到文件说一个比另一个好。 

I want to perform a string replacement on an entire column, changing all instances of one phrase to another:
 
UPDATE `some_records`
SET `some_column` = REPLACE(`some_column`, 'foo', 'bar');
 
Since many of the rows do not contain the string 'foo' they will be unaffected by this query, which is fine; I only care about the rows that do contain it. My question is, is there any reason to add a WHERE clause to explicitly target the rows that will be affected? e.g.
 
UPDATE `some_records`
SET `some_column` = REPLACE(`some_column`, 'foo', 'bar')
WHERE `some_column` LIKE '%foo%';
 
As far as I can tell, both queries have the exact same effect. Is there any advantage to the 2nd version? Does it provide better performance or any other benefits? So far I haven't found documentation to say one is better than the other.

原文：https://stackoverflow.com/questions/31666490