Handling quote within quotes in SQL statement.

1)
'select flex_value,flex_value from fnd_flex_values ffvc where ffvc.flex_value_set_id = (SELECT   flex_value_set_id
FROM   apps.fnd_flex_value_sets
WHERE   flex_value_set_name = ' 'XXGL_MGA_CB_TRANSFER_TYPE' ' ) ';


2) writing where clause

lc_defaul_clause := lc_defaul_clause || ' AND APPROVAL_STATUS = ''' || name_in('QUERY_FIND.STATUS') || '''';