JSON_QUOTE(json_val)

Quotes a string as a JSON value by wrapping it with double quote
characters and escaping interior quote and other characters, then
returning the result as a utf8mb4 string. Returns NULL if the argument
is NULL.

This function is typically used to produce a valid JSON string literal
for inclusion within a JSON document.

Certain special characters are escaped with backslashes per the escape
sequences shown in
http://dev.mysql.com/doc/refman/5.7/en/json-modification-functions.html
#json-unquote-character-escape-sequences.

URL: http://dev.mysql.com/doc/refman/5.7/en/json-creation-functions.html

