几个 SqlCommand 应用示例

string connString = "Data Source=(local);Initial Catalog=db;User Id=userId;Password=password";
using (SqlConnection conn = new SqlConnection(connString))
{
    conn.Open();
    string sql = @"delete from table1";
    using (SqlCommand cmd = new SqlCommand(sql, conn))
    {
        cmd.ExecuteNonQuery();
    }
    conn.Close();
}

string connString = "Data Source=(local);Initial Catalog=db;User Id=userId;Password=password";
using (SqlConnection conn = new SqlConnection(connString))
{
    conn.Open();
    using (SqlCommand cmd = new SqlCommand())
    {
        cmd.Connection = conn;
        cmd.CommandType = CommandType.Text;
        cmd.CommandText = @"delete from table1";
        cmd.ExecuteNonQuery();
    }
    conn.Close();
}

string connString = "Data Source=(local);Initial Catalog=db;User Id=userId;Password=password";
using (SqlConnection conn = new SqlConnection(connString))
{
    conn.Open();
    string sql = @"select * from table1";
    using (SqlCommand cmd = new SqlCommand(sql, conn))
    {
        using (SqlDataReader reader = cmd.ExecuteReader())
        {
            if (reader.Read())
            {
                id = reader.GetInt32(0);
                fld1 = reader.GetString(1);
                fld2 = reader.GetString(2);
            }
            /*
            //循环读取方式
            int i = 0;
            while (reader.Read())
            {
                ids[i] = reader.GetInt32(0);
                fld1s[i] = reader.GetString(1);
                fld2s[i] = reader.GetString(2);
                i++;
            }
            */
            reader.Close();
        }
    }
    conn.Close();
}