运行内容如下的UseDriver.java文件,
import java.sql.*;
public class UseDriver {
public static void main(String[] args) {
String url = "jdbc:mysql://localhost/sql_test ";
String userName = "root ";
String password = " ";
String sql = null;
Connection conn = null;
Statement stmt = null;
try {
//第一步：加载驱动器
Class.forName( "com.mysql.jdbc.Driver ");
} catch(ClassNotFoundException e) {
System.err.print( "ClassNotFoundException ");
}
try {
//第二步：调用DriverManager.getConnection静态方法得到数据库连接
conn = DriverManager.getConnection(url, userName, password);
//创建Statement语句
stmt = conn.createStatement();
sql = "INSERT INTO student " +
"VALUES( '12 ', 'zhangjun ', 'tianjin ', '1981-01-01 ') ";
//使用Statement语句对象执行SQL语句
stmt.executeUpdate( "DELETE FROM student WHERE stu_id= '12 ' ");
stmt.executeUpdate(sql);
System.out.println( "Insert a row successful! ");
} catch(SQLException e) {
System.err.println( "Insert SQLException ");
} finally {
//关闭语句和数据库连接
try {
stmt.close();
conn.close();
} catch(SQLException e) {
System.err.println( "Close SQLException ");
}
}
}
}
在DOS窗体下运行,不知怎么出现如下的错误,请问一下这可能是什么错误啊,谢谢!
G:\> javac UseDriver.java
G:\> java UseDriver
Insert SQLException
Exception in thread "main " java.lang.NullPointerException
at UseDriver.main(UseDriver.java:35)
------解决方案--------------------
String password = " ";
===
密码是一个空格？
------解决方案--------------------
stmt.executeUpdate( "DELETE FROM student WHERE stu_id= '12 ' ");
stmt.executeUpdate(sql);
System.out.println( "Insert a row successful! ");
} catch(SQLException e) {
e.printStch....();//这里测试一下.看看具体错在哪里了
System.err.println( "Insert SQLException ");
} finally {
------解决方案--------------------
mysql的话建议还是创建一个用户，并把相应的读写权限赋予之
根用户windows下不是 "root "吧，这个是linux下的根用户