Second, SqlCommand operation database

1.ExecuteNonQuery: Execute non-query T-SQL statement

using (SqlCommand cmd = conn.) CreateCommand ()) {      "insert INTO UserInfo (Id,username,userage,delflag) VALUES (11, ' Zhaofei ', 18,0) ";       // setting up T-SQL statements      int num = cmd. ExecuteNonQuery ();       // executes the T-SQL statement and returns the number of rows affected       Console.WriteLine (num);}

2.ExecuteScalar: Executes the query and returns the first column of the first row in the result set returned by the query

using (SqlCommand cmd = conn.) CreateCommand ()) {      "";       // Query the employee table for all information about      sex as a male Label1. Text = cmd. ExecuteScalar (). ToString ();       // executes the query and returns the first column of data in the first row of the information}

3.ExecuteReader: Executes the T-SQL statement and returns a SqlDataReader reader

using (SqlCommand cmd = conn.) CreateCommand ()) {      "select * FROM employee";       = cmd. ExecuteReader ();       // executes a T-SQL statement and generates a SqlDataReader reader       while (reader. Read ())      {         listView1.Items.Add (reader[1]. ToString ());      }       // reader[1]: reads data from column 2nd of the table       Reader. Close ();}

Second, SqlCommand operation database