Gauche DBI(Postgresql) の NULL は "" を返す。 (use dbi) (use gauche.collection) (define (select-db dbname sql) (guard (e ((<dbi-error> e) (raise e))) (let* ((conn (dbi-connect (string-append "dbi:pg:dbname=" dbname))) (result (dbi-execute (dbi-prepar</dbi-error>…