"…" or '...'
Literals are expressed as strings enclosed in single or double-quotes.
charset = character set name enclosed in single or double quotes (for example
locale = string specifying IETF BCP 47 language tag enclosed in single or double quotes (see the list IANA language subtag registry). The default locale is English.
In case the constant contains a single quote or double quote you may either use the other for enclosing (i.e: use double quotes for enclosing if the string contains a single quote or vice versa).
Alternatively, you can escape it with a preceding backslash character
\ (0x5c ASCII).
Constants are usually less interest for analytical purposes, hence in most cases, they are just matched - i.e values not exported for the query.
Matching one or more characters 'a'.