存储功能

Question

我遇到了一个问题，我试图创建一个存储函数来搜索用户的用户名和密码。该函数的参数应该是用户名和密码，如果存在用户名和密码组合，它必须返回true，如果不存在则必须返回false。这是我迄今为止创造的并没有成功：

DELIMITER ;
use db_name;
DROP procedure IF EXISTS `proc_name`;

DELIMITER $$
CREATE PROCEDURE `proc_name`(IN _insertId INT)
BEGIN

-- DISPLAYED CORRECTLY HERE
SELECT _insertId INTO @insertbuff;

SELECT 
`TABLE1_ALIAS1`.`PARAM1_ALIAS`,
`TABLE2_ALIAS2`.`PARAM2_ALIAS`,
`TABLE3_ALIAS3`.`PARAM3_ALIAS`
INTO @VAR1, @VAR2, @VAR3,
FROM `TABLE1` AS `TABLE1_ALIAS1` 
INNER JOIN `TABLE2` AS `TABLE2_ALIAS2` ON ...
JOIN `TABLE3` AS `TABLE3_ALIAS3` ON ...
-- SEEMS TO BE IGNORE IN THIS WHERE CLAUSE
WHERE `MAIN_TXN`.`id` = _insertId -- OPTION 1: NOT WORKING
-- WHERE `TABLE1`.`id` = CONCAT('', @insertbuff); -- OPTION 2: ALSO NOT WORKING


END$$
DELIMITER ;

Answer 1

您需要在函数中使用return语句来返回值。此外，对您与客户匹配的实际查询进行了小修复：

create function cred(in_username varchar(15), in_password varchar(6))
returns char(5) 
begin

declare v_cnt int;

select count(*) into v_cnt
from customers
where username = in_username and pwd = in_password;

if (v_cnt>0) then
  return 'true';
else
  return 'false';
end if;

end
$$