PreparedStatement接口

来源：互联网发布：节奏大师刷钻石软件编辑：程序博客网时间：2024/05/17 03:17

Statement接口封装了JDBC执行SQL语句的方法，可以完成Java程序执行SQL语句的操作，但在实际开发中，SQL往往需要将程序中的变量做为查询条件参数等，使用Statement接口进行操作过于繁琐，而且存在安全方面的缺陷，针对这一问题，JDBC API中封装了Statement的扩展PreparedStatement对象，它可以将Statement中的执行方法改用占位符？来代替。

一、增、删、改示例：

package jdbc;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import com.mysql.jdbc.PreparedStatement;public class InsertDemo {public static void main(String[] args) throws ClassNotFoundException {try {Class.forName("com.mysql.jdbc.Driver");String uri = "jdbc:mysql://localhost:3306/wtyy";String username = "root";String pwd = "wtyy";Connection conn = DriverManager.getConnection(uri, username, pwd);//增String sql="insert into student(name,age) values(?,?)";PreparedStatement ps=(PreparedStatement) conn.prepareStatement(sql);ps.setString(1, "张三");//对sql语句的第一个参数赋值ps.setInt(2, 18);//对sql语句的第二个参数赋值int row=ps.executeUpdate();//执行if(row>0){System.out.println("成功添加了"+row+"条数据");}ps.close();//删String sql1="delete from student where name=? and age=?";PreparedStatement ps1=(PreparedStatement) conn.prepareStatement(sql1);ps1.setString(1, "张三");ps1.setInt(2, 18);ps1.execute();ps1.close();//改String sql2="update student set age=20 where name=?";PreparedStatement ps2=(PreparedStatement) conn.prepareStatement(sql2);ps2.setString(1, "张三");ps2.execute();conn.close();} catch (SQLException e) {e.printStackTrace();}}}

二、批量操作：

一次性需要添加或者更新或者删除很多条数据时，这个数据有可能会达到几万条，这样在每次操作时都进行创建数据库的连接会开销很大的。JDBC可以进行批量的执行SQL语句，

例：

package jdbc;import java.sql.Connection;import java.sql.DriverManager;import java.sql.SQLException;import com.mysql.jdbc.PreparedStatement;public class MuchUpdate {public static void main(String[] args) throws ClassNotFoundException {try {Class.forName("com.mysql.jdbc.Driver");String uri = "jdbc:mysql://localhost:3306/wtyy";String username = "root";String pwd = "wtyy";Connection conn = DriverManager.getConnection(uri, username, pwd);//批量增String sql="insert into student(name,age) values(?,?)";PreparedStatement ps=(PreparedStatement) conn.prepareStatement(sql);ps.setString(1, "李四");ps.setInt(2, 19);ps.addBatch();ps.setString(1, "王五");ps.setInt(2, 30);ps.addBatch();ps.executeBatch();//批量改String sql1="update student set age=28 where name=?";PreparedStatement ps1=(PreparedStatement) conn.prepareStatement(sql1);ps1.setString(1, "张三");ps1.addBatch();ps1.setString(1, "王五");ps1.addBatch();ps1.setString(1, "李四");ps1.addBatch();ps1.executeBatch();//批量删String sql2="delete from student where name=?";PreparedStatement ps2=(PreparedStatement) conn.prepareStatement(sql2);ps2.setString(1, "张三");ps2.addBatch();ps2.setString(1, "王五");ps2.addBatch();ps2.executeBatch();} catch (SQLException e) {e.printStackTrace();}}}

阅读全文

1 0