【C#】ado.net常用代码

带参数的SqlDataAdapter ：

using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))
{
using (SqlCommand com = con.CreateCommand())
{
com.CommandText = "select Age from T_User where UserName=@name";
com.Parameters.Add(new SqlParameter("name", textBox1.Text));
SqlDataAdapter da = new SqlDataAdapter(com);
DataSet ds = new DataSet();
da.Fill(ds);
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}
}

　　从多个txt文件中导入数据致数据库：

using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))
{
using (SqlCommand com = con.CreateCommand())
{
con.Open();
com.CommandText = "insert into T_phone(StarNum,EndNum,Name) values(@starnum,@endnum,@name)";
if (folderBrowserDialog2.ShowDialog() == DialogResult.OK)
{
string[] files = Directory.GetFiles(folderBrowserDialog2.SelectedPath, "*.txt", SearchOption.AllDirectories);//遍历文件夹中的文件
foreach (string file in files)//遍历所选中的文件
{
string name = Path.GetFileNameWithoutExtension(file); //获取文件的文件名（不包括后缀）

string[] lines = File.ReadAllLines(file,Encoding.Default);//file和streamreader的区别在于file是把数据全部加载内存，而streamreader则是一行一行的读取，当数据量大的时候用streamreader数据量小的时候用file；
foreach (string line in lines)
{
string[] strs = line.Split('-');
string starnum = strs[0];
string endnum = strs[1];
string shengshi = strs[2];
com.Parameters.Clear();
com.Parameters.Add(new SqlParameter("starnum", starnum));
com.Parameters.Add(new SqlParameter("endnum", endnum));
com.Parameters.Add(new SqlParameter("name", name + shengshi));
com.ExecuteNonQuery();
}

}
MessageBox.Show("导入成功");
}
}

从带个txt文件中导入数据到数据库：

if (openFileDialog1.ShowDialog() == DialogResult.OK)
{
string filename = openFileDialog1.FileName;
using (FileStream file = File.OpenRead(openFileDialog1.FileName))
{
using (StreamReader reader = new StreamReader(file,Encoding.Default))
{
string line = null;
while ((line = reader.ReadLine()) != null)
{
string[] strs = line.Split('&');
string name = strs[0];
int age = Convert.ToInt32(strs[1]);

using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))
{
using (SqlCommand com = con.CreateCommand())
{
con.Open();
com.CommandText = "insert into T_User(UserName,Age) values(@username,@age)";
com.Parameters.Clear();
com.Parameters.Add(new SqlParameter("username", name));
com.Parameters.Add(new SqlParameter("age", age));
com.ExecuteNonQuery();
}
}

}
MessageBox.Show("导入成功！");
}
}

从数据库导出数据：

if (saveFileDialog1.ShowDialog() == DialogResult.OK)
{
using (StreamWriter sw = new StreamWriter(saveFileDialog1.FileName))
{
using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))
{
using (SqlCommand com = con.CreateCommand())
{
con.Open();
com.CommandText = "select * from T_User";
using (SqlDataReader read = com.ExecuteReader())
{
StringBuilder sb = new StringBuilder();
while (read.Read())
{
Int64 id = read.GetInt64(read.GetOrdinal("id"));
string name = read.GetString(read.GetOrdinal("UserName"));
int age = read.GetInt32(read.GetOrdinal("Age"));
sb.Append(id);
sb.Append(name);
sb.Append(age);
}
sw.WriteLine(sb);
}
MessageBox.Show("导出成功！");
}
}
}

}

弱类型DataSet数据的修改：

DataSet ds = new DataSet();
using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))
{
using (SqlCommand com = con.CreateCommand())
{

con.Open();
com.CommandText = "select * from T_User";
SqlDataAdapter da = new SqlDataAdapter(com);
da.Fill(ds);
DataTable dt = ds.Tables[0];
DataRow dr = dt.Rows[0];
dr["UserName"] = "你是哈哈";

SqlCommandBuilder scb = new SqlCommandBuilder(da);
da.Update(ds);

this.lianjie();
}
}

lianjie()函数：

public void lianjie()
{
DataSet ds = new DataSet();
using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))
{
using (SqlCommand com = con.CreateCommand())
{

con.Open();
com.CommandText = "select * from T_User";
SqlDataAdapter da = new SqlDataAdapter(com);
da.Fill(ds);
dataGridView1.DataSource = ds.Tables[0];
}
}
}

从数据库读取某个字段：

View Code

using (SqlConnection con = cons.getconn())
{
using (SqlCommand com = con.CreateCommand())
{
con.Open();
com.CommandText = "select C_OnePwd  from Client where C_ID=@C_ID and C_State=1";
com.Parameters.Add(new SqlParameter("C_ID", model.cid));
using (SqlDataReader reader = com.ExecuteReader())
{
if (reader.Read())
{
string password = reader.GetString(reader.GetOrdinal("C_OnePwd"));
if (password == model.conepwd)
{
return true;
}
else
{
return false;
}
}

else
{
return false;
}
}
}
}