英文:
Java JDBC: Cannot connect to SQL due to unknown database
问题
我已经能够通过Netbeans在我的旧电脑上连接到MySQL，使用以下代码：
Class.forName("com.mysql.jdbc.Driver");
String connectionUrl = "jdbc:mysql://localhost:3306/tblpizza?user=root";
Connection con = DriverManager.getConnection(connectionUrl,"root","root");
然而，自从我换了新电脑后，每次尝试运行该代码时，都会出现以下错误：
SQL 异常:
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: 未知数据库 'root'
作为一个相对新手的编程者，我尝试在线搜索不同的查询，但未能找到解决方案。
备注：
-
我尝试更改代码的不同部分，确保没有漏掉任何大写/小写字母。
-
我进入了MYSQL并运行了一个命令来检查所有数据库名称，并确保复制了正确的数据库名称。
-
无论我如何更改代码，它总是显示"未知数据库 'root'"，即使我没有将root作为数据库名称输入。
任何帮助将不胜感激！
英文:
So I've been able to connect to MySQL through Netbeans on my older computer, using the following code:
Class.forName("com.mysql.jdbc.Driver");
String connectionUrl = "jdbc:mysql://localhost:3306/tblpizza?user=root";
Connection con = DriverManager.getConnection(connectionUrl,"root","root");
However, since getting a new computer, every time I try to run the code, it comes up with this error:
> SQL Exception:
> com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown
> database 'root'
Being fairly new to coding in general, I tried researching different queries online but couldn't come up with a solution.
Notes:
-I tried changing different sections of my code, making sure I didn't miss any upper case/lower case letters
-I went onto MYSQL and ran a command to check all the database names, and made sure to copy the right one down
-No matter how I change the code in anyway, it always says "unknown database 'root'" even though I haven't put root down as the database name
Any help would be greatly appreciated!
答案1
得分: 0
您的数据库URL不应包含?user=root后缀。
请将其修改为以下形式，因为您已经在getConnection(url, username, password)调用中指定了用户名/密码。
String connectionUrl = "jdbc:mysql://localhost:3306/tblpizza";
英文:
Your database URL should not have the ?user=root suffix.
Make it look like so, as you are specifying the username/password already in the getConnection(url, username, password) call.
String connectionUrl = "jdbc:mysql://localhost:3306/tblpizza";
答案2
得分: 0
因为在创建con对象时下一步需要用户名和密码，所以在连接url中不应该指定它。
请尝试在连接url中去除?user=root，然后运行以下代码：
String connectionUrl = "jdbc:mysql://localhost:3306/tblpizza";
英文:
Since it is asking from username and password in next step while making con object you should not specify it in connection url.
Try to run code by removing the ?user=root from your connection url.
String connectionUrl = "jdbc:mysql://localhost:3306/tblpizza";
答案3
得分: 0
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/tblpizza","root","root");
尝试这种方式，你可以省略connectionUrl变量。
英文:
Class.forName("com.mysql.jdbc.Driver");
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/tblpizza","root","root");
Try this way, you can omit the connectionUrl variable.
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