縮短數據訪問代碼......這會工作嗎？

Question

我正在查詢數據，如果數據不存在，我插入它。如果是這樣，我做別的：

SqlCommand checkHead = new SqlCommand("SELECT * FROM TABLE WHERE ORDER_NO = '" + orderNo + "';", connection); 
SqlDataReader checkHeadReader = checkHead.ExecuteReader(CommandBehavior.SingleRow); 

if (!checkHeadReader.HasRows) 
{ 
    checkHeadReader.Close(); 
    addHead.ExecuteNonQuery(); 
} 

但我不知道是否有一個更短的方式來編碼？下面的代碼會工作嗎？

SqlCommand checkHead = new SqlCommand("SELECT * FROM TABLE WHERE ORDER_NO = ' + orderNo + "';", connection); 

if(checkHead.ExecuteReader(CommandBehavior.SingleRow).HasRows) 
    addHead.ExecuteNonQuery(); 
else //this order already exists 
    Server.Transfer(@"~/Views/Error.aspx"); 

Answer 1

ExecuteScalar非常適合這一點，例如，

using (SqlCommand cmdCheck = new SqlCommand("Select Count(*) From Table Where Order_No = '" + orderNo + "'", connection)) 
{ 
    int nExists = (int)cmdCheck.ExecuteScalar(); 
    if (nExists==0) addHead.ExecuteNonQuery(); 
}