数据库的增删改查操作

与之前的工具类放在同一个包下。

package com.weixuan.project;

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

/**
 * 与数据库相关的增删改查操作
 * 
 * @author 韦轩
 * 
 */
public class CRUD {

public static void main(String[] args) {
try {
new CRUD().read();
//new CRUD().create();
new CRUD().update();

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

// CREATE 从数据库读取操作,即查找
static void create() throws SQLException {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
st = conn.createStatement();
String sql = "insert into mytable(username,age,sex,hobby,ID) values('weihang',20,'男','玩游戏',null)";
int co = st.executeUpdate(sql);
System.out.println("co = "+co);
} finally {
JdbcUtils.free(rs, st, conn);
}
}

// read 从数据库读取操作,即查找
static void read() throws SQLException {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
st = conn.createStatement();
rs = st.executeQuery("select * from mytable");
while (rs.next()) {
System.out.println(rs.getObject("ID") + "\t" + rs.getObject("username")
+ "\t" + rs.getObject("sex"));
}
} finally {
JdbcUtils.free(rs, st, conn);
}
}

// update 从数据库读取操作,即查找
static void update() throws SQLException {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
st = conn.createStatement();
String sql = "update mytable set age = age+10";
int i = st.executeUpdate(sql);
System.out.println("i = "+i);
} finally {
JdbcUtils.free(rs, st, conn);
}
}

// delete 从数据库读取操作,即查找
static void delete() throws SQLException {
Connection conn = null;
Statement st = null;
ResultSet rs = null;
try {
conn = JdbcUtils.getConnection();
st = conn.createStatement();
String sql = "delete from mytable where age >42";
int i = st.executeUpdate(sql);
System.out.println("i = "+i);
} finally {
JdbcUtils.free(rs, st, conn);
}
}
}