JDBC操作数据库

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package cn.com.JDBC;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class CRUD {
public static void main(String[] args) throws SQLException {
// TODO Auto-generated method stub
//create();
//update();
delete();
read();
}
static void delete() throws SQLException
{
Connection conn=null;
Statement st=null;
ResultSet resultset=null;
try {
//2.建立连接
conn=JdbcUtils.getConnection();
//单例设计模式
conn=JdbcUtilsSingle.getInstance().getConnection();
//3.创建语句
st=conn.createStatement();
//4.执行语句
String sql="delete from user where id>5";
int i=st.executeUpdate(sql);
System.out.println("i="+i);
} finally
{
JdbcUtils.free(resultset, st, conn);
}
}
static void update() throws SQLException
{
Connection conn=null;
Statement st=null;
ResultSet resultset=null;
try {
//2.建立连接
conn=JdbcUtils.getConnection();
//单例设计模式
conn=JdbcUtilsSingle.getInstance().getConnection();
//3.创建语句
st=conn.createStatement();
//4.执行语句
String sql="update user set money=money+20";
int i=st.executeUpdate(sql);
System.out.println("i="+i);
} finally
{
JdbcUtils.free(resultset, st, conn);
}
}
static void create() throws SQLException
{
Connection conn=null;
Statement st=null;
ResultSet resultset=null;
try {
//2.建立连接
conn=JdbcUtils.getConnection();
//单例设计模式
conn=JdbcUtilsSingle.getInstance().getConnection();
//3.创建语句
st=conn.createStatement();
//4.执行语句
String sql="insert into user(name,birthday,money) values('wy','2011-09-23','2894656')";
int i=st.executeUpdate(sql);
System.out.println("i="+i);
} finally
{
JdbcUtils.free(resultset, st, conn);
}
}
static void read() throws SQLException
{
Connection conn=null;
Statement st=null;
ResultSet resultset=null;
try {
//2.建立连接
conn=JdbcUtils.getConnection();
//单例设计模式
conn=JdbcUtilsSingle.getInstance().getConnection();
//3.创建语句
st=conn.createStatement();
//4.执行语句
resultset=st.executeQuery("select id,name,birthday,money from user");
//5.处理结果
while(resultset.next())
{
System.out.println(resultset.getObject("id"));
System.out.println(resultset.getObject("name"));
System.out.println(resultset.getObject("birthday"));
System.out.println(resultset.getObject("money"));
}
} finally
{
JdbcUtils.free(resultset, st, conn);
}
}
}
package cn.com.JDBC;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class JdbcUtils
{
private static String url="jdbc:mysql://localhost:3306/jdbc";
private static String user="root";
private static String password="123";
private JdbcUtils()
{
}
static
{
try
{
Class.forName("com.mysql.jdbc.Driver");
}
catch(ClassNotFoundException e)
{
throw new ExceptionInInitializerError(e);
}
}
public static Connection getConnection() throws SQLException
{
return DriverManager.getConnection(url, user, password);
}
public static void free(ResultSet resultset,Statement st,Connection conn)
{
//6.释放资源
try{
if(resultset!=null)
resultset.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally
{
try
{
if(st!=null)
st.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
finally
{
if(conn!=null)
try {
conn.close();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
}

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