How do I find out all databases starting with ‘mysql’ to which I have access to?

Using following query you can find out all databases starting with “mysql”.

SHOW DATABASES LIKE ‘mysql%’;

What do you mean by % and _ in the LIKE statement?

% corresponds to 0 or more characters, _ is exactly one character in the LIKE statement.

What are the column comparisons operators?

The = , <>, <=, <, >=, >,<<,>>, <=>, AND, OR or LIKE operators are used in column comparisons in SELECT statements.

What is the difference between the LIKE and REGEXP operators?

LIKE and REGEXP operators are used to express with ^ and %.

Example:
SELECT * FROM table WHERE column REGEXP “^x”;
SELECT * FROM table WHERE column LIKE “%x”;