Question

c# 数据库 int num=Convert.ToInt32(command.ExecuteScalar());cuowu

using System.Data.SqlClient;
namespace 连接数据库
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
String name=this.textBox1.Text;
String password=this.textBox2.Text;
//获得数据库连接字符串
String coon = @"Data Source=JJ\SQLEXPRESS;Initial Catalog=jonas;Integrated Security=True";
//创建sqlconnection 对象
SqlConnection connection=new SqlConnection(coon);
String sql=String.Format("select count(8) from Login where username='0',and password='1'",name,password);

// 创建sqlcommand对象
SqlCommand command=new SqlCommand(sql,connection);
connection.Open();
int num = Convert.ToInt32(command.ExecuteScalar());
try
{
if(num>0)
{
MessageBox.Show("登陆成功！");
}
else
{
MessageBox.Show("登陆失败！");

}
}
catch (Exception ex)
{

MessageBox.Show("异常错误"+ex);
}
finally
{
connection.Close();
}
}
}
}
这些是我从视频上学习的，但是在点击登录的时候是错的，提示：
System.Data.SqlClient.SqlException”类型的未经处理的异常在 System.Data.dll 中发生;
奇怪？是数据库权限不够还是什么？望大神指点一下....
后来试着把 int num = Convert.ToInt32(command.ExecuteScalar());
放进try里面 点登录又提示

Answer 1

这句错了：String sql=String.Format("select count(8) from Login where username='0',and password='1'",name,password);
改成：String sql=String.Format("select count(8) from Login where username={0},and password={1}",name,password);

追问

好了，谢谢你

Answer 2

String sql=String.Format("select count(8) from Login where username='0',and password='1'",name,password);

改成

String sql=String.Format("select count(8) from Login where username='{0}' and [password]='{1}'",name,password);