使用jdbc来实现一个简单的增删改查
package com.database;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import com.entity.Admin;
public class AdminDBHelp {
// 根据id来修改数据
public void modify(Admin a) throws SQLException {
Connection coon = null;
PreparedStatement preparedStatement = null;
try {
coon = DBOpenClose.openConnection();
String sql = "UPDATE admin SET username ='" + a.getUsername()
+ "',password='" + a.getPassword()
+ "'WHERE id = " + a.getId();
preparedStatement = coon.prepareStatement(sql);
preparedStatement.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
DBOpenClose.release(null, coon, preparedStatement);
}
}
//插入数据
public void update(Admin admin) throws SQLException {
Connection coon = null;
PreparedStatement preparedStatement = null;
try {
coon = DBOpenClose.openConnection();
String sql = "INSERT INTO admin(username,password)" + "VALUES(?,?)";
preparedStatement = coon.prepareStatement(sql);
preparedStatement.setString(1, admin.getUsername());
preparedStatement.setString(2, admin.getPassword());
preparedStatement.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
DBOpenClose.release(null, coon, preparedStatement);
}
}
// 根据id来删除数据
public void delete(int id) throws SQLException {
Connection coon = null;
PreparedStatement preparedStatement = null;
try {
coon = DBOpenClose.openConnection();
String sql = "DELETE FROM admin WHERE id =" + id;
preparedStatement = coon.prepareStatement(sql);
preparedStatement.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
DBOpenClose.release(null, coon, preparedStatement);
}
}
//查询数据
public ArrayList<Admin> query() {
Connection coon = null;
Statement statement = null;
ResultSet rs = null;
ArrayList<Admin> list = new ArrayList<Admin>();
try {
coon = DBOpenClose.openConnection();
statement = coon.createStatement();
String sql = " SELECT id,username,password " + "FROM admin";
rs = statement.executeQuery(sql);
while (rs.next()) {
Admin admin = new Admin();
admin.setId(rs.getInt(1));
admin.setUsername(rs.getString(2));
admin.setPassword(rs.getString(3));
list.add(admin);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
DBOpenClose.release(rs, coon, statement);
}
return list;
}
}