问题描述
我有一个registration.php页面,我做,我需要检查一个用户名是否已经在我的数据库,所以我不会有2个成员相同的名称...
I have a registration.php page I made and I need to check if a username is already in my database so that I won't have 2 members with the same name...
这是我如何将用户信息插入数据库(用户名,密码,注册日期等):
Here is how I am inserting the user info into the database (username, password, date of registration, etc.):
mysql_query("INSERT INTO UserDb (ID, TimeStamp, UserName, Password) VALUES ('$ipaddress', NOW(), '$user_username', '$user_password')");
如何检查UserName字段下的数据库UserDb以确保用户的变量$ user_username尚不存在?
How can I check that database "UserDb" under the "UserName" field to make sure the user's variable "$user_username" doesn't already exist?
推荐答案
您可以使数据库中的用户名字段成为主键或唯一,这保证了数据库中的用户名唯一性。
You can make the username field in the database a primary key or unique, which guarantees the username uniqueness in the database.
然后,如果您尝试插入已存在的用户名。
Then, if you try to insert an already existing username the mysql_query() function will fail, returning FALSE.
应该总是使用一个简单的select语句查询数据库中是否存在用户名:
Besides that, you should always query the database for the existence of the username, using a simple select statement:
SELECT username FROM table WHERE username ='$ php_username_var' ;
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