Question

我想在数据库中查找重复的成员。

首先，我想检查一下他们的用户名是否存在。
如果没有，我想查看他们的名字，姓氏和电子邮件地址。
最后，如果这与任何人都不匹配，我想检查是否存在名字和姓氏。

我一直在关注IF / ELSE声明甚至是Google中的CASE，但我似乎无法弄清楚它在我的情况下会如何起作用。

这里有一些代码在我看来是有意义的（作为一个PHP程序员），但它不是MySQL做的事情......

SELECT id FROM members WHERE (
    IF (member_username = 'john.doe')
    ELSEIF (member_firstname = 'John' AND member_lastname = 'Doe' AND member_email = 'john@doe.com')
    ELSE (member_firstname = 'John' AND member_lastname = 'Doe')
) AND deleted = 0

如果可能的话，我如何将上述内容转换为有效的MySQL代码。

Answer 1

我最终接受了@ Corbin的建议并使用了

SELECT username, first_name, last_name, email_addr FROM members WHERE username = 'username' OR (first_name = 'first name' AND last_name = 'last name')

然后使用PHP if / else语句来确定哪个记录是完全重复的。

Answer 2

这会有什么问题？

SELECT id
FROM members
WHERE (member_username = 'john.doe'
    OR (member_firstname = 'John' AND member_lastname = 'Doe' AND member_email = 'john@doe.com')
    OR (member_firstname = 'John' AND member_lastname = 'Do'))
AND deleted = 0

Answer 3

不要忘记 TOP 1！

SELECT TOP 1 id FROM members WHERE deleted = 0 AND
(
  (member_username = 'john.doe') OR
  (member_email = 'john@doe.com' AND member_firstname = 'John' AND member_lastname = 'Doe') OR
  (member_firstname = 'John' AND member_lastname = 'Doe')
)

Answer 4

看看这个：http://docs.oracle.com/cd/E17952_01/refman-5.5-en/control-flow-functions.html#operator_case

WHERE中的MySQL IF / ELSE语句

4 个答案: