string sqlConnStr = "Data Source=服務(wù)器名;Initial Catalog=數(shù)據(jù)庫(kù)名;User ID=用戶名;Password=密碼";//用戶密碼登錄
//或
string sqlConnStr = "Data Source=服務(wù)器名;Initial Catalog=數(shù)據(jù)庫(kù)名;Integrated Security=true;//主機(jī)用戶登錄 IntegratedSecurity這個(gè)字段表示是否使用用戶名密碼登錄

using System.Data.SqlClient;

SqlConnection sqlConnection = new SqlConnection(sqlConnStr);

try
{
	sqlConnection.Open();
}
catch(Exception ex)
{
    Console.WriteLine(ex.Message);
}

string sql = "select 1";
SqlCommand cmd = new SqlCommand();//創(chuàng)建SQL語(yǔ)句處理對(duì)象
//或SqlCommand cmd = new SqlCommand(sql,sqlConnection);//構(gòu)造函數(shù)綁定
cmd.Connection = sqlConnection;//綁定連接
cmd.CommandText = sql;//綁定SQL語(yǔ)句
int count = (int)cmd.ExecuteScalar();

string sql = "select 1,2,3";
//省略綁定
SqlDataReader sqlDataReader = cmd.ExecuteReader();//數(shù)據(jù)對(duì)象
while (sqlDataReader.Read())//read方法 ：前進(jìn)到下一條記錄  并且是否有下一行記錄
{
    int a =(int)sqlDataReader[0];
    int a =(int)sqlDataReader[1];
    int a =(int) sqlDataReader[2];//索引從0開(kāi)始，按單元格檢索
    // int a = sqlDataReader["字段名"];使用數(shù)據(jù)庫(kù)中的字段名同樣可以
}

string sql = delete from [數(shù)據(jù)庫(kù)];
//省略綁定步驟
int line = cmd.ExecuteNonQuery();//返回記錄更改的行數(shù)

if (sqlDataReader != null)
{
    sqlDataReader.Close();
}
if (cmd != null)
{
    cmd.Dispose();
}
if (sqlConnection != null)
{
    sqlConnection.Close();
}

insert into [表名](字段1，字段2···) values(值1，值2···);

delete from [表名] where [條件]

update [表名] set 字段名 = 值 ，第二個(gè)修改 where [條件]

select * from [數(shù)據(jù)庫(kù)] where [字段名] = 值;