VB.net最好用于查询变量QUERY或我应该使用DA

Question

Which is better to use for query 1 or 2 give me some tips. I have a gridview that has a lot of info like hundreds. Which is advisable to use for fast querying the result without lagging

1. QUERY = "SELECT * FROM exdb.sample"

OR

2. DA = New MySqlDataAdapter("SELECT * FROM exdb.sample", dataCNN)

Answer 1

If I am right you are talking about Connected and Disconnected Architecture,

Connected Architecture : you have to declare the connection explicitly by using Open(), and close the connection using Close(), and u cn execute commands using different methods like.. ExecuteNonQuery,ExecuteScalar,ExecuteReader etc..

Disconnected Architecture: you dont need to define the connections explicitly..SqlDataAdatpter itself can open and closes the connection..and u can use dataset for storing the info. temporarily and Fill method was used to execute the commands give in adapter...

• When you use DataAdapter , there's no requirement of opening and closing connection. It's done automatically.
• By keeping connections open for only a minimum period of time, ADO .NET conserves system resources and provides maximum security for databases and also has less impact on system performance.
• Only one operation can be performed at a time in connected environment while in dissconnected multiple operations can be performed.

But as you said there are hudreds of records in your application I'll suggest to use DataReader (ie Connected Architecture ) as it is faster than DataAdapter (ie Disconnected Architecture ) beacause it is read-only, forward-only stream of data. I'll suggest you go through this for more information about DataReader and DataAdapter .

Answer 2

First one is a connected architecture where you will loop through all the rows, populate them to a DataTable and attach to your gridview.

Whereas, second one is disconnected architecture using a data adapter; you maintain the structure in memory.

I would go for the second approach, fill the dataset/datatable and bind the same source to gridview.