MySQL: Difference between ', `, ´ and "

Question

When seeing SQL code on the internet and in manuals there seems to vary a lot what is used to signify strings (or at least that's what I think they do?).

Are there any difference between using `, ´, ' or "? Are they all the same? Or do some of them have special meanings? Should some be used in certain cases and others in other cases? What is the deal here?

Answer 1

`` delimits identifiers and ' and " delimits strings. there are no difference between last two

´ has no meaning in mysql

Answer 2

Backticks (`) are required when identifiers, such as column names, are using names which also happen to be reserved words. For example, since from is a reserved word, you would have to wrap a from column name in backticks, as follows:

SELECT `from`, to FROM messages WHERE to = 'Joe';

Also note how the string in the WHERE clause had to be wrapped in quotes. This is also required.

Further reading:

• Reserved Words in MySQL 5.1