第一次调试成功:
数据表student:
容易出故障的几个点,
1.import不全
2.mysql时区问题。
2020-7-3补充查询功能
public static void update() //增删改功能
public static void query() //查询功能
代码如下:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import com.mysql.cj.protocol.Resultset;
public class JDBCDemo{
private static final String URL="jdbc:mysql://localhost:3306/lds?serverTimezone=UTC";
private static final String USERNAME="root";
private static final String PWD="prolific";
//
public static void update() {//增删改
Connection connection = null;
Statement stmt =null;
ResultSet rs=null;
try {
// a.导入驱动,加载具体的驱动类
Class.forName("com.mysql.cj.jdbc.Driver");//加载具体的驱动类
// b.与数据库建立连接
connection = DriverManager.getConnection(URL,USERNAME,PWD);
//c.发送sql,执行(增、删、改、查)
stmt=connection.createStatement();
String sql="insert into student values(10,'Xiaolingnv',32,'Xiagu') ";
//String sql="update student set STUNAME='Gaiming' where stuno=2";
//String sql="delete from student where stuno=4";
int count = stmt.executeUpdate(sql); //返回值标是增删改几条数据
//查询是stmt.executeQuery(sql);
//d.处理结果
if (count>0){
System.out.println("操作成功!");
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}catch(Exception e){
e.printStackTrace();
}
finally{
try {
if (stmt!=null) stmt.close(); //对象.方法
if (connection!=null) connection.close();
}catch(SQLException e) {
e.printStackTrace();
}
}
}
public static void query() {//查询功能
Connection connection = null;
Statement stmt =null;
ResultSet rs=null;
try {
// a.导入驱动,加载具体的驱动类
Class.forName("com.mysql.cj.jdbc.Driver");//加载具体的驱动类
// b.与数据库建立连接
connection = DriverManager.getConnection(URL,USERNAME,PWD);
//c.发送sql,执行(增、删、改、查)
stmt=connection.createStatement();
String sql="select stuno,stuname from student";
rs=stmt.executeQuery(sql);
//查询是stmt.executeQuery(sql);
//int count = stmt.executeUpdate(sql); //返回值标是增删改几条数据
//d.处理结果
/*
if (count>0){
System.out.println("操作成功!");
}
*/
while(rs.next()) {
// int sno=((ResultSet) rs).getInt("stuno");
// String sname=rs.getString("stuname");
int sno=rs.getInt(1);
String sname=rs.getString(2);
System.out.println(sno+"------"+sname);
}
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}catch(Exception e){
e.printStackTrace();
}
finally{
try {
if(rs!=null) rs.close();
if (stmt!=null) stmt.close(); //对象.方法
if (connection!=null) connection.close();
}catch(SQLException e) {
e.printStackTrace();
}
}
}
public static void main(String[] args){
update();
query();
}
}