Question

我已经编写了以下函数，但是当我运行它时它没有返回任何内容。有人可以帮助确定问题吗？

CREATE OR REPLACE FUNCTION GenerateReadableRandomString (
len INT
) RETURNS varchar AS
$$
DECLARE
validchars VARCHAR;
randomstr VARCHAR;
randint INT;
i INT;

BEGIN

validchars := 'ABCEFHJKLMNPRTWXY3478';
i := 0;

LOOP
    randint := ceil(random() * char_length(validchars));
    randomstr := randomstr || substring(validchars from randint for 1);
    i := i + 1;
    EXIT WHEN i = len;
END LOOP;

RETURN randomstr;
END;
$$
LANGUAGE plpgsql;

Answer 1

更快的代码可以

CREATE OR REPLACE FUNCTION rstr(int)
RETURNS text AS $$
SELECT array_to_string(ARRAY(SELECT substring('ABCEFHJKLMNPRTWXY3478' FROM (random()*21)::int + 1 FOR 1) 
                                FROM generate_series(1,$1)),
                       '') 
$$ LANGUAGE sql;

Answer 2

是的问题是你没有初始化你的变量randomstr。当你用null结束某些东西时你会得到null

plpgsql函数生成随机可读字符串

2 个答案: