Question

我的java项目中有2个文件：MysqlConnect和Main。我想从Main类运行查询。这可能吗？

这是MysqlConnect文件：

public class MysqlConnect {

public Connection conn = null;
public String url = "jdbc:mysql://localhost:3306/";
public String dbName = "jdbctutorial";
public String driver = "com.mysql.jdbc.Driver";
public String userName = "birthday";
public String password = "123456";
public Statement stmt;
public String query = "";
public int rs;

public void crearedatabase() {
    try {

        Class.forName(driver).newInstance();
        conn = DriverManager
                .getConnection(url + dbName, userName, password);
        // System.out.println("Connected to the database");
        Statement stmt = conn.createStatement();

    } catch (Exception e) {
        System.out.println("Baza de date nu a fost creata");
    }

}

public void executeSql() {

    try {
        rs = stmt.executeUpdate(query);
    } catch (Exception e) {
        System.out.println("Mysql Error");
    }

}
}

这是 主文件 ：

public class Main {
public static void main(String[] args) throws SQLException
{



MysqlConnect sqlconnect = new MysqlConnect();   
sqlconnect.crearedatabase();

sqlconnect.query="INSERT INTO `jdbctutorial`.`persons` (`id`, `nume`, `prenume`, `data`) VALUES (NULL, 'xxxx', 'xxxx', '1990-12-12');";
sqlconnect.executeSql();
}

}

错误（异常）位于try / catch

的MysqConnection上

rs = stmt.executeUpdate(query);

Answer 1

将语句对象分配给名为stmt的局部变量，而不是具有相同名称的对象字段。替换此

Statement stmt = conn.createStatement();

有了这个：

this.stmt = conn.createStatement();

this在这里不是必需的，但将它放在那里是一种很好的做法。

如何从主文件中将数据插入数据库？

1 个答案: