JDBC对数据库的增删改查

package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

/*
* insert
* */
public class JDBC1 {
    public static void main(String[] args) {
        Statement sta = null;
        Connection conn = null;

        try {
            //注册驱动
            Class.forName ("com.mysql.jdbc.Driver");
         //定义sql
         String sql = "insert into test values(40)";
         //获取执行sql的对象
            conn = DriverManager.getConnection ("jdbc:mysql:///db","root","123456");
            //获取执行Sql的对象Statement
            sta = conn.createStatement ();
            //执行语句
            int count = sta.executeUpdate (sql);
            //处理结果
            System.out.println (count);

        } catch (ClassNotFoundException e) {
            e.printStackTrace ();
        } catch (SQLException e) {
            e.printStackTrace ();
        }finally {
            if(sta!=null){
                try {
                    sta.close ();
                } catch (SQLException e) {
                    e.printStackTrace ();
                }
            }
            if(conn!=null){
                try {
                    conn.close ();
                } catch (SQLException e) {
                    e.printStackTrace ();
                }
            }
        }

    }
}

package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

//修改表记录
public class JDBC2 {
    public static void main(String[] args) {
        Statement sat = null;
        Connection conm = null;
        //注册驱动
        try {
            Class.forName ("com.mysql.jdbc.Driver");
            //获取执行的Mysql对象
             conm = DriverManager.getConnection ("jdbc:mysql:///db","root","123456");
            //定义Sql语句
            String sql = "update test set r1=10";
            //获取sql对象
             sat = conm.createStatement ();
            //执行sql语句
            int count = sat.executeUpdate (sql);
            //处理结果
            System.out.println (count);
        } catch (ClassNotFoundException e) {
            e.printStackTrace ();
        } catch (SQLException e) {
            e.printStackTrace ();
        }finally {
            try {
                sat.close ();
                conm.close ();
            } catch (SQLException e) {
                e.printStackTrace ();
            }
        }

    }

}

package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;

/*
* test 表删除一条记录
*
* */
public class JDBC3 {
    public static void main(String[] args) {
        Connection conn = null;
        Statement sat = null;
        try {
            //注册驱动
            Class.forName ("com.mysql.jdbc.Driver");
            //获取连接对象
             conn = DriverManager.getConnection ("jdbc:mysql:///db","root","123456");
            //编写sql语句
            String sql = "delete from test where id = 1";
            String sql1 = "insert into test values(1,40)";
            //获取sql对象
            sat = conn.createStatement ();
            //执行sql语句
            int count = sat.executeUpdate (sql);
            int count1 = sat.executeUpdate (sql1);
            //打印结果
            System.out.println (count);
        } catch (ClassNotFoundException e) {
            e.printStackTrace ();
        } catch (SQLException e) {
            e.printStackTrace ();
        }finally {
            try {
                sat.close ();
                conn.close ();
            } catch (SQLException e) {
                e.printStackTrace ();
            }

        }
    }
}

package cn.itcast.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.sql.Statement;
/*
* 创建表练习
*
* */
public class JDBC4 {
    public static void main(String[] args) {
        Connection conn = null;
        Statement sat = null;
        try {
            //注册驱动
            Class.forName ("com.mysql.jdbc.Driver");
            //获取连接对象
            conn = DriverManager.getConnection ("jdbc:mysql:///db","root","123456");
            //定义sql语句
            String sql = "create table test1(id int ,name varchar(20))";
            //获取Sql对象
            sat =  conn.createStatement ();
            //执行sql语句
            int count = sat.executeUpdate (sql);
            System.out.println (count);
        } catch (ClassNotFoundException e) {
            e.printStackTrace ();
        } catch (SQLException e) {
            e.printStackTrace ();
        }finally {
            try {
                sat.close ();
                conn.close ();
            } catch (SQLException e) {
                e.printStackTrace ();
            }
        }
    }
}