C# 私人笔记

 

 

1.ADO.NET 连接数据库的模版

string constr = "data source=127.0.0.1\mysql2008;database=dbtest;integrated security=true";
try
{
using (SqlConnection con=new SqlConnection(constr))
{
string sql = "delete from sys_gwdt where id=''";
using (SqlCommand com = new SqlCommand(sql, con))
{
try
{
if (con.State == System.Data.ConnectionState.Closed)
{
con.Open();////数据库越晚打开越好
}
//int r = com.ExecuteNonQuery();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
finally 
{
con.Close();
con.Dispose();
}
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}

 

2.  dateTimePicker1.Value = DateTime.Now.AddDays(1 - DateTime.Now.Day);   //月初

 

 

3. 

DataRow dr = myDataSet.Tables["ds"].NewRow();
dr[1] = "-----全部科室-----";
myDataSet.Tables["ds"].Rows.InsertAt(dr, 0);
cmbDepartment.DisplayMember = "KSMC";
cmbDepartment.ValueMember = "KSID";
cmbDepartment.DataSource = myDataSet.Tables["ds"].Copy();

 

 

 

4. 数据库导出到文本，文本导入到数据库

 

private void button1_Click(object sender, EventArgs e)
{
//把TblArea中的数据导出到文本文件
string constr = "Data Source=steve-pc;Initial Catalog=itcast2013;Integrated Security=True";
using (SqlConnection con = new SqlConnection(constr))
{
string sql = "select * from TblArea";
using (SqlCommand cmd = new SqlCommand(sql, con))
{
con.Open();
using (SqlDataReader reader = cmd.ExecuteReader())
{
if (reader.HasRows)
{

//创建一个StreamWriter用来写数据
using (StreamWriter sw = new StreamWriter("area.txt", false, Encoding.UTF8))
{
while (reader.Read())
{
int id = reader.GetInt32(0);
string city = reader.GetString(1);
int pid = reader.GetInt32(2);
sw.WriteLine(string.Format("{0},{1},{2}", id, city, pid));
}
this.Text = "导出成功！";
}


}
else
{
this.Text = "没有查询到任何数据";
}
}
}

}
}

private void button2_Click(object sender, EventArgs e)
{
//导入
//1.读取文本文件
using (StreamReader reader = new StreamReader("area.txt"))
{
string constr = "Data Source=steve-pc;Initial Catalog=itcast2013;Integrated Security=True";
using (SqlConnection con = new SqlConnection(constr))
{
string sql = "insert into NewArea1 values(@name,@pid)";
using (SqlCommand cmd = new SqlCommand(sql, con))
{
//建议每次都设置设置参数的数据类型，更保险。
SqlParameter pname = new SqlParameter("@name", SqlDbType.NVarChar, 50);
SqlParameter pid = new SqlParameter("@pid", SqlDbType.Int);

cmd.Parameters.Add(pname);
cmd.Parameters.Add(pid);

con.Open();
string line;
//循环读取每一行
while ((line = reader.ReadLine()) != null)
{
//Console.WriteLine(line);
//把每行数据按照","分割，提取每一列的信息
string[] columns = line.Split(',');
cmd.Parameters[0].Value = columns[1];
cmd.Parameters[1].Value = columns[2];

cmd.ExecuteNonQuery();
}
}


}


}
MessageBox.Show("导入完毕！");

}