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Should i use SqlConnection to connect to server before i use SqlDataAdapter to to fill the dataset ?
Example :
=============
<br />
string ConStr = "server=(local);uid=sa;pwd=password;database=NorthWind";<br />
string cmdString = "select top 3 last name, firstname, title from employees";<br />
SqlConnection conn = new SqlConnection(ConStr);<br />
SqlCommand com = new SqlCommand(cmdString,con);<br />
SqlDataAdapter da = new SqlDataAdapter(com);<br />
DataSet ds = new DataSet();<br />
<br />
conn.open();
<br />
da.Fill(ds);<br />
I try code above and i found that even without manuall open the connection i still able to fill up the dataadapter (da).
So what is the best method to fill the dataadapter with out connection first out without using connection?
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If your connection is closed already - the DataAdapter will open the connection, perform the query, and close the connection again. If you do not need the connection open for anything else then I recommend you let the DataAdapter do the clean up for you.
[ADDITIONAL] I should add that if the connection is already open the DataAdapter will not close it [/ADDITIONAL]
If you are going to perform a series of queries one-after-the-other then I would recommend that you open the connection, perform your queries, then close the connection.
Does this help?
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Thanks it really help and clear all my doubt.
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here is my problem, please help.
I am having 2 databases namely employees and projects.
employees database contains a table emp (with fields like empname, etc).
projects database contains a table prj (with fields like prjname, prj_leader, etc).
but i want to ensure that ALL the prj_leader entries MUST be existing empnames of emp table in employees database.
i know that if both the tables are in the same database, it is simple. but i have no idea whether we can set such foreign key constraints across databases.
kindly suggest.
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I’m afraid, its not possible. But,you can use Procedure to ensure this.
With regards,
Nazmul Hassan Hirok
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I've been working on this little Windows Forms app. that manages data using a DataGrid. Up until now I've only tested it with small datasets (it connects to an Access Database (and yes, there is a reason for not using MSDE)). Everything has been fine until I finally got the real, official data put together (it was comprised of 5 spreadsheets, all in different formats, with no validation  ) and plugged it in for the first time.
I cannot believe how slow it is now  . The DataAdapter's Fill method is taking anywhere from 20 to 40 seconds to load the dataset with the 26000 records. Obviously the solution is to only grab the data I need to fill the current view and then intercept the applicable scroll events and re-fill the data as necessary (similar to paging with the web version). I'm about to embark on that but I'm wondering: is this all really necessary? It seems like something that should be built into the framework. Needless to say I don't want to reinvent the wheel so if someone knows what I'm missing, could you enlighten me please?
I've looked at virtually every example I can find and they all say that the Fill method is slow and offer a couple of tips for speeding it up: using the overridden Fill method that accepts a start and row count is one. Nobody bothers to go into any more detail than just mentioning it, however.
Thanks in advance.
Cheers,
Drew.
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Did you try SqlDataReader?
If you are using DataGrids should be the fastest way.
Cheers
Al
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I have a need to pack 8 seperate datasets into one of 9 arrays for population in a tree control. Is this possible? if not what would be the best way to accomplish this? I am accessing 5-6 fields from seperate tables for each ds and need to aggregate them at a later point!
My end goal will have 9 nodes in a tree, using the first ds as one node and branch the the rest in sequential order.
Thought / Suggestions?
Thanks;
David @ Premier
You are only as good as your last project.
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hi,
I am having 2 databases namely employees and projects.
employees database contains a table emp (with fields like empname, etc)
projects database contains a table prj (with fields like prjname, prj_leader, etc).
but i want to ensure that ALL the prj_leader entries MUST be existing empnames of emp table in employees database.
i know that if both the tables are in the same database, it is simple. but i have no idea whether we can set such foreign key constraints across databases.
kindly suggest.
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hi
I have got a table as follows
col1 col2
---- -------
1 1183.74
2 1188.05
3 1202.08
4 1211.92
5 1213.55
6 1213.45
7 1213.54
8 1204.92
9 1210.13
10 1209.57
11 1205.45
12 1194.65
13 1194.22
14 1203.21
15 1205.72
16 1203.38
17 1198.68
18 1188
19 1189.24
20 1182.81
21 1177.07
22 1190.25
23 1191.17
now i want a query which yields the following results
here col3 for record 1 is calculated as follows
(1188.08/1183.74)-1)*100=0.364100225
col1 col2 col3
---- ---- ----------------
1 1183.74 0.364100225
2 1188.05 1.180926729
3 1202.08 0.818581126
4 1211.92 0.134497327
5 1213.55 -0.008240287
6 1213.45 0.007416869
7 1213.54 -0.710318572
8 1204.92 0.432393852
9 1210.13 -0.04627602
10 1209.57 -0.340616913
11 1205.45 -0.89593098
12 1194.65 -0.035993806
13 1194.22 0.752792618
14 1203.21 0.208608639
15 1205.72 -0.19407491
16 1203.38 -0.390566571
17 1198.68 -0.890980078
18 1188 0.104377104
19 1189.24 -0.540681444
20 1182.81 -0.485285042
21 1177.07 1.119729498
22 1190.25 0.077294686
23 1191.17 
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Looks like homework...
Wout Louwers
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hi
I want to know how to communicate with database over the internet. What type of encrypting should I use.
shelly
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Although it is possible (if your firewall allows it) I wouldn't really recommend it. You can, of course, connect via a VPN which would make it appear as if it is on a local network. VPN software will encrypt the data for you.
If the communication is at an application level I would suggest looking into creating a web service to communicate with the database. This uses HTTP (so you can use HTTPS) and also it means that you define exactly the type of queries that can be run by virtue of the web methods that you expose.
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Hello,
Please advise on how I might be able to make this sproc work...
declare @TrainerID int
select TrainerID, LastName, FirstName, City, State, Country, r.code, l.description, p.Code from trainers as t
inner join Regions as r
on t.region = r.regionid
inner join Languages as l
on t.Language1 = l.LangID
--and t.Language2 = l.LangID
--and t.Language3 = l.LangID
inner join products as p
on t.product1 = p.ProductID
--on t.product2 = p.ProductID
--on t.product3 = p.ProductID
--on t.product4 = p.ProductID
where TrainerID = @TrainerID
The situation is that I have designed in the Trainers (t) table multiple columns of Languages and Products with properties as Int which stores values based on their respective LanguageID and ProductID from the Languages and Products (definition) table.
The dilemma is on the result, I would like to see the actual codes and not the ID key of each of the multiple columns coming from the definition tables.
Thanks
Jay
Feng Screwed - the art of moving to a new place because the old place is just too messy to clean.
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Please disregard the previous message, I was able to figure it out.
I do have another question though. What if l3 is null from db, then how do evaluate it in sproc so that if it is len = 0, then it is left blank instead of not returning any result.
Thanks 
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The Trainer table is somewhat denormalised (it partially meets the 3rd normal form criteria) and it would be better if there was a many-to-many join between the Trainer table and the Languages table, and also between the Trainer table and the Products table.
To implement a many-to-many join you add an intermediate table with a compound primary key and two foreign joins. This is actually a lot simpler than it sounds. Simply put the intermediate table contains the primary key from each side of the join, for example the primary key from Trainer (one of the foreign keys) and the primary key from Languages (the other foreign key). All those columns together make up the primary key of the intermediate table so that the only columns in the intermediate table make up the compound primary key.
So, you create two new tables like this
/----------------------\ /---------------------\
| TrainerLanguage | | TrainerProduct |
|----------------------| |---------------------|
| PK, FK1 | TrainerID | | PK, FK1 | TrainerID |
| PK, FK2 | LanguageID | | PK, FK2 | ProductID |
\----------------------/ \---------------------/ and populate them with the values that were in the Language and Product columns in the Trainer table.
Once you have that set up then your queries can be much simpler and you don't have to worry about nulls and the schema will be much more flexible than it is at the moment.
I don't know your level with databases so I hope that this is not too overwhelming.
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Hello everyone I am working on a small project I'm sorry if I do not know all the right phrases and words that goes with the programming language I'm still learning with that behind us. I need help with my project had created a database with access and now I want to fill it with data through the form that I have created I have implemented the fill method if I go into the database and add and name address telephone number eccentrics and when I go back to my form and hit the load button to fill method works I conceded that what I can not get is my form to write the new data back to the database I am using VB.net and yes I went to server Explorer and made a connection to the database. adapter, data connection, dataset what I don't know is what is my code supposed to look like to get my data to write back to the data source
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what programming language are you using?
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I get this error:
Description Line 1: Incorrect syntax near '='.
Explantation Syntax error in reserved words!
SQL Statement
SELECT m.[Firstname], m.[Lastname], m.[Address], m.[PostalCode], p.[PostalOffice], m.[Email], m.[MemberImage], m.[categoryid]
FROM [Member] m, [Post] p WHERE m.[PostalCode]=p.[PostalCode] AND m.[MemberId]=
I use this code
sqlStatement = ""<br />
sqlStatement = sqlStatement & "SELECT m.[Firstname], m.[Lastname], m.[Address], m.[PostalCode], p.[PostalOffice], m.[Email], m.[MemberImage], m.[categoryid] "<br />
sqlStatement = sqlStatement & "FROM [Member] m, [Post] p "<br />
sqlStatement = sqlStatement & "WHERE m.[PostalCode]=p.[PostalCode] AND m.[MemberId]=" & intMemberId
Have someone poposal whats it's wrong 
Thanks for any help
Erik Gjertsen
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intMemberId is not a proper SQL variable.
Try @intMemberID.
See Colin's comment above - I have to second that (LOUDLY).
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Change the intMemberId with number,
Erik Gjertsen wrote:
sqlStatement = sqlStatement & "WHERE m.[PostalCode]=p.[PostalCode] AND m.[MemberId]=2"
From there you will probably find out what went wrong.
<italic>Work hard, Work effectively and a bit of luck is the key to success.
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As part of my "newbee" problems I discovered I can't compile visual basic as cut and paste from examples:
The example:
Dim selectCMD As OleDbCommand = New OleDbCommand("SELECT CustomerID, CompanyName FROM Customers", nwindConn)
has be modified as such in order to compile:
Dim selectCMD As System.Data.OleDb.OleDbCommand = New System.Data.OleDb.OleDbCommand("SELECT CustomerID, CompanyName FROM Customers", nwindConn)
Am I missing some header file or something else?
Thanks,
Ilan
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