使用java jdbc和prepared语句的CREATE DATABASE查询返回语法错误 [英] CREATE DATABASE query using java jdbc and prepared statement returns syntax error

问题描述

我正在尝试让Java使用JDBC创建数据库但是我得到了语法错误，尽管查询是正确的。例如，如果我明确地将数据库的名称写入代码中，它就可以正常工作。这是我的代码：

I am trying to get Java to create a database using JDBC but I get a syntax error, despite the query being correct. If I write the name of a database into the code explicitly, for example, it works fine. Here's my code:

package mysql_manipulator;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

public class Create {
    private static final String 
            driver = "com.mysql.jdbc.Driver",
            url = "jdbc:mysql://localhost",
            username = "dylan",
            password = "******";
    private String databaseName;

    public Create (){
        this.databaseName = null;
    }

    public String getDatabaseName() {
        return databaseName;
    }

    public void setDatabaseName(String databaseName) {
        this.databaseName = databaseName;
    }

    public void createDatabase(String databaseName){
        try {
            this.setDatabaseName(databaseName);        
            Class.forName(driver);
            Connection con = DriverManager.getConnection(url,username, 
                password);
            String query = "CREATE DATABASE ?";
            PreparedStatement preparedStmt = con.prepareStatement(query);
            preparedStmt.setString (1,this.getDatabaseName());
            preparedStmt.execute();
            preparedStmt.close();
            con.close();        
        }
        catch (Exception anException){
            System.out.println("Error: " + anException);
        }
    }
}  

我的主要课程

package mysql_manipulator;

public class Mysql_manipulator {
    public static void main(String[] args) {
        Create myObj = new Create();
        myObj.createDatabase("whatevs");        
    }    
}

错误

Error: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You  have an error in
your SQL syntax; check the manual that corresponds to your  MariaDB server version 
for the right syntax to use near ''whatevs'' at line 1

非常感谢任何知道为什么不起作用的人 - 我在网上搜索都无济于事。

Huge thanks to anyone who knows why this isn't working - I've searched all over the web to no avail.

推荐答案

您不能将数据库名称作为绑定变量 - 您必须将其嵌入查询文字中。请将您的查询更改为：

You cannot have the database name as a bind variable -- you have to embed it in the query literal. Change your query into this instead:

String query = "CREATE DATABASE " + getDatabaseName();

您还可以使用普通的语句（而不是 PreparedStatement ）来运行这个SQL。

You can also use a plain Statement (instead of PreparedStatement) for running this SQL.

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