几个简单地连接数据库案例,巩固练习用
2014-12-19 17:19
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1.用户登陆,输错3次锁定角色;
string connstr = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
using( SqlConnection conn = new SqlConnection(connstr))
{
conn.Open();
using(SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "select * from [user] where username = @unm";
SqlParameter[] parameters = {new SqlParameter("@unm",txtName.Text)} ;
cmd.Parameters.AddRange(parameters);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
adapter.Fill(ds);
DataRowCollection rows = ds.Tables[0].Rows;
string password;
string id;
//当用户名存在且不重复时间
if (rows.Count ==1)
{
password = (string)rows[0]["password"];
id = (string)rows[0]["uid"];
if (String.Equals(password,txtPassword.Text))//当用户名和密码都输入正确时
{
MessageBox.Show("login success!");
}
else//当密码输入错误时
{
cmd.CommandText = "update [user] set errortimes = errortimes+1 where uid = @id";
cmd.Parameters.Add("@id",id);
cmd.ExecuteNonQuery();
MessageBox.Show("sorry,the password is not true!");
}
int num = (int)rows[0]["errortimes"];
if (num >= 3)//如果密码输错超过3次
{
MessageBox.Show("wrong number has limited,the user is locked!");
return;
}
}
else if (rows.Count > 1) //用户名重复
{
throw new Exception("error:the username is repetition!");
}
else //用户名不存在
{
MessageBox.Show("sorry,the user is not exist!");
}
}
}
2. 省级联动查询
3.文本文件数据导入
private void txtImport_Click(object sender, RoutedEventArgs e)
{
OpenFileDialog ofd = new OpenFileDialog(); //打开浏览
ofd.Filter = "文本文件|*.txt";//文本选择过滤 txt文件
bool flag = (bool)ofd.ShowDialog();//看视频是不用转换的,不知为何。ShowDialog 表示选择的是txt文件,返回true
if(flag == false)
{
return;
}
string name = ofd.FileName; //选择文件的名称
//IEnumerable<string> lines = File.ReadLines(name,Encoding.Default); //IEnumerable 是一个集合
string[] lines = File.ReadLines(name, Encoding.Default).ToArray(); //读取选中文件内容,保存到string数组中
SqlConnection conn;
using( conn = new SqlConnection("Data Source=.;Initial Catalog=exercise;User Id=sa;Password=123456"))
{
conn.Open();
SqlCommand cmd = conn.CreateCommand();
for (int i = 0; i < lines.Count(); i++)
{
string line = lines[i];
string[] tels = line.Split('\t'); //将读取到的每一行以制表符分割成数组
Int64 tel = Convert.ToInt64(tels[0]);
string telAddr = tels[1];
//Sqlhelps.ExecuteNonQuery("insert into tel values(@tel,@telAddr)",new SqlParameter("@tel",tel),new SqlParameter("@telAddr",telAddr));
cmd.CommandText = "insert into tel(tel,telAddr) values(@tel,@add)";
cmd.Parameters.Clear();
cmd.Parameters.AddRange(new SqlParameter[]{new SqlParameter("@tel",tel),new SqlParameter("@add",telAddr)});
cmd.ExecuteNonQuery();
}
}
conn.Close();
MessageBox.Show("数据导入成功");
}
***导入到一半的时候报错,不知为何
string connstr = ConfigurationManager.ConnectionStrings["connstr"].ConnectionString;
using( SqlConnection conn = new SqlConnection(connstr))
{
conn.Open();
using(SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "select * from [user] where username = @unm";
SqlParameter[] parameters = {new SqlParameter("@unm",txtName.Text)} ;
cmd.Parameters.AddRange(parameters);
SqlDataAdapter adapter = new SqlDataAdapter(cmd);
DataSet ds = new DataSet();
adapter.Fill(ds);
DataRowCollection rows = ds.Tables[0].Rows;
string password;
string id;
//当用户名存在且不重复时间
if (rows.Count ==1)
{
password = (string)rows[0]["password"];
id = (string)rows[0]["uid"];
if (String.Equals(password,txtPassword.Text))//当用户名和密码都输入正确时
{
MessageBox.Show("login success!");
}
else//当密码输入错误时
{
cmd.CommandText = "update [user] set errortimes = errortimes+1 where uid = @id";
cmd.Parameters.Add("@id",id);
cmd.ExecuteNonQuery();
MessageBox.Show("sorry,the password is not true!");
}
int num = (int)rows[0]["errortimes"];
if (num >= 3)//如果密码输错超过3次
{
MessageBox.Show("wrong number has limited,the user is locked!");
return;
}
}
else if (rows.Count > 1) //用户名重复
{
throw new Exception("error:the username is repetition!");
}
else //用户名不存在
{
MessageBox.Show("sorry,the user is not exist!");
}
}
}
2. 省级联动查询
3.文本文件数据导入
private void txtImport_Click(object sender, RoutedEventArgs e)
{
OpenFileDialog ofd = new OpenFileDialog(); //打开浏览
ofd.Filter = "文本文件|*.txt";//文本选择过滤 txt文件
bool flag = (bool)ofd.ShowDialog();//看视频是不用转换的,不知为何。ShowDialog 表示选择的是txt文件,返回true
if(flag == false)
{
return;
}
string name = ofd.FileName; //选择文件的名称
//IEnumerable<string> lines = File.ReadLines(name,Encoding.Default); //IEnumerable 是一个集合
string[] lines = File.ReadLines(name, Encoding.Default).ToArray(); //读取选中文件内容,保存到string数组中
SqlConnection conn;
using( conn = new SqlConnection("Data Source=.;Initial Catalog=exercise;User Id=sa;Password=123456"))
{
conn.Open();
SqlCommand cmd = conn.CreateCommand();
for (int i = 0; i < lines.Count(); i++)
{
string line = lines[i];
string[] tels = line.Split('\t'); //将读取到的每一行以制表符分割成数组
Int64 tel = Convert.ToInt64(tels[0]);
string telAddr = tels[1];
//Sqlhelps.ExecuteNonQuery("insert into tel values(@tel,@telAddr)",new SqlParameter("@tel",tel),new SqlParameter("@telAddr",telAddr));
cmd.CommandText = "insert into tel(tel,telAddr) values(@tel,@add)";
cmd.Parameters.Clear();
cmd.Parameters.AddRange(new SqlParameter[]{new SqlParameter("@tel",tel),new SqlParameter("@add",telAddr)});
cmd.ExecuteNonQuery();
}
}
conn.Close();
MessageBox.Show("数据导入成功");
}
***导入到一半的时候报错,不知为何
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