1.oracle splicing a single quote:
Normal writing: '' '' ||
Because of escaped single quotes, the first and the last one is to specify the characters you want to use, and the second 'is a single quote escape character, so you need a third' is the real you that to be spliced.
It can also be used chr (39) as a mosaic character, so that it may be more intuitive.
2.oracle replace single quotes
REPLACE('a,b',',',chr(39) || ',' || chr(39))
Here will be replaced with ','
For example: the need for a, b replaced by 'a', 'b' can write:
select chr(39) || REPLACE('a,b',',',chr(39) || ',' || chr(39)) || chr(39) from dual
The results above.