What’s the difference between VARCHAR and CHAR?

VARCHAR is variable-length. CHAR is fixed length. If your content is a fixed size, you’ll get better performance with CHAR. See the MySQL page on CHAR and VARCHAR Types for a detailed explanation (be sure to also read the comments).

ERROR 1698 (28000): Access denied for user ‘root’@’localhost’

Some systems like Ubuntu, MySQL is using the UNIX auth_socket plugin by default. Basically it means that: db_users using it, will be “authenticated” by the system user credentials. You can see if your root user is set up like this by doing the following: As you can see in the query, the root user is using the auth_socket plugin. There are two ways to solve this: … Read more

MySQL query String contains

Quite simple actually: The % is a wildcard for any characters set (none, one or many). Do note that this can get slow on very large datasets so if your database grows you’ll need to use fulltext indices.