【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);

                    ··············

                    ··············



                }

            }

　　从多个txt文件中导入数据致数据库：

 1             using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))

 2             {

 3                 using (SqlCommand com = con.CreateCommand())

 4                 {

 5                     con.Open();

 6                     com.CommandText = "insert into T_phone(StarNum,EndNum,Name) values(@starnum,@endnum,@name)";

 7                     if (folderBrowserDialog2.ShowDialog() == DialogResult.OK)

 8                     {

 9                         string[] files = Directory.GetFiles(folderBrowserDialog2.SelectedPath, "*.txt", SearchOption.AllDirectories);//遍历文件夹中的文件

10                         foreach (string file in files)//遍历所选中的文件

11                         {

12                             string name = Path.GetFileNameWithoutExtension(file); //获取文件的文件名（不包括后缀）

13 

14                             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；

15                             foreach (string line in lines)

16                             {

17                                 string[] strs = line.Split('-');

18                                 string starnum = strs[0];

19                                 string endnum = strs[1];

20                                 string shengshi = strs[2];

21                                 com.Parameters.Clear();

22                                 com.Parameters.Add(new SqlParameter("starnum", starnum));

23                                 com.Parameters.Add(new SqlParameter("endnum", endnum));

24                                 com.Parameters.Add(new SqlParameter("name", name + shengshi));

25                                 com.ExecuteNonQuery();

26                             }

27                             

28                         }

29                         MessageBox.Show("导入成功");

30                     }

31                 }

从带个txt文件中导入数据到数据库：

 1             if (openFileDialog1.ShowDialog() == DialogResult.OK)

 2             {

 3                 string filename = openFileDialog1.FileName;

 4                 using (FileStream file = File.OpenRead(openFileDialog1.FileName))

 5                 {

 6                     using (StreamReader reader = new StreamReader(file,Encoding.Default))

 7                     {

 8                         string line = null;

 9                         while ((line = reader.ReadLine()) != null)

10                         {

11                             string[] strs = line.Split('&');

12                             string name = strs[0];

13                             int age = Convert.ToInt32(strs[1]);

14 

15                             using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))

16                             {

17                                 using (SqlCommand com = con.CreateCommand())

18                                 {

19                                     con.Open();

20                                     com.CommandText = "insert into T_User(UserName,Age) values(@username,@age)";

21                                     com.Parameters.Clear();

22                                     com.Parameters.Add(new SqlParameter("username", name));

23                                     com.Parameters.Add(new SqlParameter("age", age));

24                                     com.ExecuteNonQuery();

25                                 }

26                             }

27                            

28                         }

29                         MessageBox.Show("导入成功！");

30                     }

31                 }

从数据库导出数据：

 1             if (saveFileDialog1.ShowDialog() == DialogResult.OK)

 2             {

 3                 using (StreamWriter sw = new StreamWriter(saveFileDialog1.FileName))

 4                 {

 5                     using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))

 6                     {

 7                         using (SqlCommand com = con.CreateCommand())

 8                         {

 9                             con.Open();

10                             com.CommandText = "select * from T_User";

11                             using (SqlDataReader read = com.ExecuteReader())

12                             {

13                                 StringBuilder sb = new StringBuilder();

14                                 while (read.Read())

15                                 {

16                                     Int64 id = read.GetInt64(read.GetOrdinal("id"));

17                                     string name = read.GetString(read.GetOrdinal("UserName"));

18                                     int age = read.GetInt32(read.GetOrdinal("Age"));

19                                     sb.Append(id);

20                                     sb.Append(name);

21                                     sb.Append(age);

22                                 }

23                                 sw.WriteLine(sb);

24                             }

25                             MessageBox.Show("导出成功！");

26                         }

27                     }

28                 }

29                 

30             }

弱类型DataSet数据的修改：

 1             DataSet ds = new DataSet();

 2             using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))

 3             {

 4                 using (SqlCommand com = con.CreateCommand())

 5                 {

 6 

 7                     con.Open();

 8                     com.CommandText = "select * from T_User";

 9                     SqlDataAdapter da = new SqlDataAdapter(com);

10                     da.Fill(ds);

11                     DataTable dt = ds.Tables[0];

12                     DataRow dr = dt.Rows[0];

13                     dr["UserName"] = "你是哈哈";

14 

15                     SqlCommandBuilder scb = new SqlCommandBuilder(da);

16                     da.Update(ds);

17 

18                     this.lianjie();

19                 }

20             }

lianjie()函数：

 1         public void lianjie()

 2         {

 3             DataSet ds = new DataSet();

 4             using (SqlConnection con = new SqlConnection("server=.; database=data; integrated security=SSPI;"))

 5             {

 6                 using (SqlCommand com = con.CreateCommand())

 7                 {

 8 

 9                     con.Open();

10                     com.CommandText = "select * from T_User";

11                     SqlDataAdapter da = new SqlDataAdapter(com);

12                     da.Fill(ds);

13                     dataGridView1.DataSource = ds.Tables[0];

14                 }

15             }

16         }

从数据库读取某个字段：

View Code

 1             using (SqlConnection con = cons.getconn())

 2             {

 3                 using (SqlCommand com = con.CreateCommand())

 4                 {

 5                     con.Open();

 6                     com.CommandText = "select C_OnePwd  from Client where C_ID=@C_ID and C_State=1";

 7                     com.Parameters.Add(new SqlParameter("C_ID", model.cid));

 8                     using (SqlDataReader reader = com.ExecuteReader())

 9                     {

10                         if (reader.Read())

11                         {

12                             string password = reader.GetString(reader.GetOrdinal("C_OnePwd"));

13                             if (password == model.conepwd)

14                             {

15                                 return true;

16                             }

17                             else

18                             {

19                                 return false;

20                             }

21                         }

22 

23                         else

24                         {

25                             return false;

26                         }

27                     }

28                 }

29             }