What makes the big difference between a backtick and an apostrophe?

Question

What is the reason that the following two queries give wildly different results?

MariaDB [mydatabase]> SELECT COUNT(DISTINCT(`price`)) FROM `products`; --         


        

Answer 1

A straight single quote (') is used for string literals (along with straight double quote (")).

A backtick quote (`) is for quoting identifiers.

Identifiers must be quoted if they match a reserved word, or if they contain special characters. Quoted identifiers also can specify lowercase in case-insensitive fields (which otherwise might be shown as uppercase).

CREATE TABLE MyTable (Field INT);
DESCRIBE MyTable;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| FIELD   | INT         | YES  |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+

See also ANSI quote mode.