Question

目前我正在使用以下代码：

$sql = sprintf("SELECT * FROM users WHERE email = '%s' and password = '%s'", $email, $password);

我想完成以下任务：

$sql = sprintf("SELECT * FROM database1.users AND database2.users WHERE email = '%s' and password = '%s'", $email, $password);

我需要检查两个表中是否存在用户。

有关如何处理此事的任何建议吗？

Answer 1

您可以使用UNION组合两个查询：

SELECT * FROM database1.users WHERE email = '%s' and password = '%s'
UNION
SELECT * FROM database2.users WHERE email = '%s' and password = '%s'

Answer 2

您的查询可以如下：

SELECT table1.*, table2.* FROM table1 JOIN table2
ON table1.userID=table2.userID WHERE email=? AND password=? LIMIT 1

将变量附加到SQL查询是非常危险的，虽然您在使用sprintf时很有意义，但它无法实现您的意图。使用prepared statement来正确防范SQL注入。

Answer 3

SELECT IF(A.UserFound*B.UserFound=0,'No','Yes') Authenticated
FROM
(
    SELECT COUNT(1) UserFound FROM database1.users
    WHERE email = '%s' and password = '%s'
) A,
(
    SELECT COUNT(1) UserFound FROM database2.users
    WHERE email = '%s' and password = '%s'
) B;

检查2个数据库表以进行用户登录

3 个答案: