public static void AddData()
{
int res = -1;
//1.連接通道的連接字符串
string str = "server=.;database =test;uid=sa;pwd=chy19900909";
//2.連接通道對象
SqlConnection conn = new SqlConnection(str);
//string sql = "insert into [User] values (2,'chengyuan',23,null)"; //易錯點:如果數據庫表名是User這樣的關鍵詞要注意加[]
string sql2 = "insert into Name values(2,'chengyuan')";
SqlCommand cmd = new SqlCommand(sql2, conn);
//3.打開通道
conn.Open();
res = cmd.ExecuteNonQuery();
//關閉通道
conn.Close();
if (res > 0)
{
Console.WriteLine("數據庫更新成功");
}
else
{
Console.WriteLine("數據庫更新失敗");
}
Console.ReadKey();
}
public static void QuerySingle()
{
SqlConnection con = new SqlConnection(conStr);
//string sqlStr = "select count(*) from Book";
string sqlStr = "select * from Book";
SqlCommand cmd = new SqlCommand(sqlStr, con);
con.Open();
//調用此方法,獲得查詢語句在數據庫執行後得到的結果集的第一個單元格的值,返回類型是object
object obj = cmd.ExecuteScalar();
con.Close();
Console.WriteLine(obj.ToString());
}
public static void QueryListByDrIndex() //查詢多行數據--DataReader,逐行讀取,通過下標訪問列
{
SqlConnection con = new SqlConnection(conStr);
string sqlStr = "select * from Book";
SqlCommand cmd = new SqlCommand(sqlStr, con);
con.Open();
//調用此方法 獲得一個 讀取器對象
SqlDataReader dr = cmd.ExecuteReader();
if (dr.HasRows)//如果結果集有數據行,則爲true,否則爲false
{
while (dr.Read())//read方法,如果讀到下一行數據,則返回true,而且dr本身就等於那一行數據
{
Console.WriteLine(dr[0].ToString() + "_" + dr[1].ToString() + "_" + dr[2].ToString());
}
}
else Console.WriteLine("無數據");
dr.Close();//關閉讀取器
con.Close();//關閉連接通道
}