JDBC系列：（3）使用PreparedStatement执行sql语句

1、执行Insert语句

package com.rk.db.c_prepared;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.PreparedStatement;
import com.rk.db.utils.JDBCUtil;

/**
* 使用PreparedStatement执行Insert语句
* @author RK
*/
public class Demo01
{
public static void main(String[] args)
{
Connection conn = null;
PreparedStatement pstmt = null;
try
{
//1.获取连接
conn = JDBCUtil.getConnection();

//2.准备预编译的sql
String sql = "INSERT INTO T_Persons(UserName,Pwd) VALUES(?,?)";

//3.执行预编译sql语句(检查语法)
pstmt = conn.prepareStatement(sql);

//4.设置参数值: 参数位置  从1开始
pstmt.setString(1, "地球人");
pstmt.setString(2, "987");

//5.发送参数，执行sql
int count = pstmt.executeUpdate();
System.out.println("影响了"+count+"行！");
}
catch (SQLException e)
{
e.printStackTrace();
}
finally
{
//关闭资源
JDBCUtil.close(conn, pstmt, null);
}
}
}

2、执行Update语句

package com.rk.db.c_prepared;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.PreparedStatement;
import com.rk.db.utils.JDBCUtil;

/**
* 使用PreparedStatement执行Update语句
* @author RK
*/
public class Demo02
{
public static void main(String[] args)
{
Connection conn = null;
PreparedStatement pstmt = null;
try
{
//1.获取连接
conn = JDBCUtil.getConnection();

//2.准备预编译的sql
String sql = "UPDATE T_Persons SET UserName=?, Pwd=? WHERE Id=?";

//3.执行预编译sql语句(检查语法)
pstmt = conn.prepareStatement(sql);

//4.设置参数值: 参数位置  从1开始
pstmt.setString(1, "火星人");
pstmt.setString(2, "456");
pstmt.setInt(3, 5);

//5.发送参数，执行sql
int count = pstmt.executeUpdate();
System.out.println("影响了"+count+"行！");
}
catch (SQLException e)
{
e.printStackTrace();
}
finally
{
//关闭资源
JDBCUtil.close(conn, pstmt, null);
}
}
}

3、执行Delete语句

package com.rk.db.c_prepared;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.PreparedStatement;
import com.rk.db.utils.JDBCUtil;

/**
* 使用PreparedStatement执行Delete语句
* @author RK
*/
public class Demo03
{
public static void main(String[] args)
{
Connection conn = null;
PreparedStatement pstmt = null;
try
{
//1.获取连接
conn = JDBCUtil.getConnection();

//2.准备预编译的sql
String sql = "DELETE FROM T_Persons WHERE Id=?";

//3.执行预编译sql语句(检查语法)
pstmt = conn.prepareStatement(sql);

//4.设置参数值: 参数位置  从1开始
pstmt.setInt(1, 5);

//5.发送参数，执行sql
int count = pstmt.executeUpdate();
System.out.println("影响了"+count+"行！");
}
catch (SQLException e)
{
e.printStackTrace();
}
finally
{
//关闭资源
JDBCUtil.close(conn, pstmt, null);
}
}
}

4、执行Select语句

package com.rk.db.c_prepared;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.PreparedStatement;
import com.rk.db.utils.JDBCUtil;

/**
* 使用PreparedStatement执行Select语句
* @author RK
*/
public class Demo04
{
public static void main(String[] args)
{
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
try
{
//1.获取连接
conn = JDBCUtil.getConnection();

//2.准备预编译的sql
String sql = "SELECT * FROM T_Persons";

//3.执行预编译sql语句(检查语法)
pstmt = conn.prepareStatement(sql);

//4.执行sql语句,得到返回结果
rs = pstmt.executeQuery();

//5.输出
while(rs.next())
{
int id = rs.getInt("Id");
String userName = rs.getString("UserName");
String pwd = rs.getString("Pwd");
System.out.println(id + "\t" + userName + "\t" + pwd);
}
}
catch (SQLException e)
{
e.printStackTrace();
}
finally
{
//关闭资源
JDBCUtil.close(conn, pstmt, rs);
}
}
}

5、思维导图