使用C#控制台程序操作SQL Serve 的3种基本方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;

namespace FirstClass
{
public class SQLHelper
{
public int RunSql(string s)
{
SqlConnection sql = new SqlConnection("Data Source=.;Initial Catalog=School;User ID = sa; Password = a451601308");
sql.Open();
SqlCommand cmd = new SqlCommand(s, sql);
int num = cmd.ExecuteNonQuery();  //返回受影响的行数
sql.Close();
return num;

}
public int Runsql1(string s)
{
SqlConnection sql = new SqlConnection("Data Source=.;Initial Catalog=School;User ID = sa; Password = a451601308");
sql.Open();
SqlCommand cmd = new SqlCommand(s, sql);
int num = (int)cmd.ExecuteScalar(); //返回第一行第一列的值
sql.Close();
return num;
}
public void Runsql2(string s)
{
SqlConnection sql = new SqlConnection("Data Source=.;Initial Catalog=School;User ID = sa; Password = a451601308");
sql.Open();
SqlCommand cmd = new SqlCommand(s, sql);
SqlDataAdapter dr = new SqlDataAdapter(cmd);
DataSet t = new DataSet();
dr.Fill(t, "Student"); //"Student"取名，建议与表名相同
DataTable dt = t.Tables[0];     //返回多行多列
for (int i = 0; i < dt.Rows.Count; i++)
{
Console.WriteLine(dt.Rows[i]["StudentName"].ToString());
}
}
public void Runsql3(string s)
{
SqlConnection sql = new SqlConnection("Data Source=.;Initial Catalog=School;User ID = sa; Password = a451601308");
sql.Open();
SqlCommand cmd = new SqlCommand(s, sql);
SqlDataReader dr = cmd.ExecuteReader();   //返回多行多列
while (dr.Read())
{
Console.WriteLine(dr["StudentName"].ToString());
}
}
}
}