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I wanna fetch some data from a database. The data I want is lying in different tables.
My Question is
Is it better to use a single query containing joins than using different queries to fetch that data
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Use the joins. Joins are not in themselves complext, however the data model can be.
"If a man empties his purse into his head, no man can take it away from him, for an investment in knowledge pays the best interest." -- Joseph E. O'Donnell
Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!
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It is better to drink water than coffee. 
If you mean, "is it going to be faster to run a single query", then the answer is "yes, almost always".
If you mean, "is it going to be easier to run multiple queries", then the answer to that is also "yes, almost always".
If you mean, "which of the options is going to solve world hunger and remove GW Bush from office", then I would have to say "neither, unless you're progamming the bush-cheney 2004 web-site".
my blog
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I want to write a function what use ado.net update database. in the function,
it can check record automatically then insert or update database.Have some better method?
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Create a stored procedure that does the check and if acceptable insert or update the record. Call the stored procedure from your .NET application.
If necessary you can return success or failure values back to your .NET application if you need to know if the insert/update was successful or if the check denied the update and so on.
"If a man empties his purse into his head, no man can take it away from him, for an investment in knowledge pays the best interest." -- Joseph E. O'Donnell
Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!
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Hi friends...
i installed Microsoft Data Engine (MSDE) 1.0 in my machine...but this will not start the service automatically, so i searched in microsoft site and according to them..
Scm.exe Utility Examples
The following are examples that use the Scm.exe utility to start, stop, and modify the MSSQLServer Service:
Start the MSSQLServer Service
scm -Action 1 -Service mssqlserver
i tried this many times with that SCM.exe, but what the hell that again popups the syntax screen..!!!what is wrong with ?? their documentation or scm.exe.?????
please help me..!!!!
i would like to name the next generation of c++ as c++++ 
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renjith_sree wrote:
i would like to name the next generation of c++ as c++++
I think you are too late - Microsoft already named it C# (if you notice the # symbol can be made up of 4 + symbols)
"If a man empties his purse into his head, no man can take it away from him, for an investment in knowledge pays the best interest." -- Joseph E. O'Donnell
Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!
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Colin Angus Mackay wrote:
Microsoft already named it C# (if you notice the # symbol can be made up of 4 + symbols)
are you joking..?? c# is the next generation of c ++ ??
i never saw such an ugly syntaxed language...
if they do so they killed the beautiness of c++
that looks like a silly script..!!!!
yuck..!!!
if you really eager to know about the next gen of c, search for the laguage named 'D'. thats really nice ..!!!
would like to name the next generation of c++ as c++++
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renjith_sree wrote:
are you joking..??
About C# being the next generation of C++? Only partly. Microsoft did use the sharp (it is supposed to be the musical sharp Unicode 266F rather than the hash character) because it can be split into 4 plus symbols. And Microsoft are selling it on the idea that it is a step forward from C++
renjith_sree wrote:
i never saw such an ugly syntaxed language...
Yeah! I know all those curly braces are really horrible. 
renjith_sree wrote:
if they do so they killed the beautiness of c++
Have you been taking Enlish lessons from an American? Lets take a noun "beauty" and modify it so it is.... A noun! Ergo: Beautiness. It like color becomes colorize (for a verb) and colorization (for a noun) despite the fact that color is both a verb and a noun.
As for C++, what IS beautiful about C++?
renjith_sree wrote:
that looks like a silly script..!!!!
Not as silly as VB.NET!
renjith_sree wrote:
if you really eager to know about the next gen of c, search for the laguage named 'D'.
I've heard of 'D' already. However, it is unlikely to put food on my table or a roof over my head so I'll stick with C# thanks.
"If a man empties his purse into his head, no man can take it away from him, for an investment in knowledge pays the best interest." -- Joseph E. O'Donnell
Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!
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Hi, writing what should be simple enough programme to access MS Access table in C. Using Borland (unfortunate constraints dictate this). I have downloaded all the neccesary header files and SDKs available for ODBC. Programme is written and compiles without errors or warnings however when I ask to make or build project. All my SQL functions are declared unresolved by the linker. I think I might be missing a file called bodbc32.dll, a link library for Borland when using ODBC.
Below is an example of the error message.
[Linker Error] Unresolved external 'SQLBindParameter' referenced from C:\DOCUMENTS AND SETTINGS\LAWRED2\MY DOCUMENTS\WORK FOLDER\PROGRAMMES\SERIAL\SERIALREADER.OBJ
If someone could explain this. Maybe it is the fact I am missing the link library. Anyone know of it, have experience of this sort of lark, anyone have that file. Google doesnt give one page about bodbc32.lib.
Help!!
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You are missing a required .lib file for linking. I think if you check the file SERIALREADER.c (or what ever source type it might be), it is likely #including a header file like bodbc32.h or something like that. If you can then find the location of that header file, there should be a directory above that include directory,like 'LIB' that would normally contain the .lib file to link with.
That's my best guess to start with.
Chris Meech
I am Canadian. [heard in a local bar]
I think people should be required to have an operator's permit to use the internet. John Simmons
I have a feeling that if the millions of man hours wasted every year by geeks trying to get various video and sound cards working under Linux were put into some useful endeavor we'd have solved world hunger, we'd have peace and aids would be no more. [JOS poster]
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O.K., here's my question, and please forgive me if it has been asked before. I have a database that that stores user details (username / PAssword) in an Access database in a table called Trader, I am wring a front end application in C# (first time!) that needs to get from a user via a window form and store the values in variables i.e.
string Password(label Password)
string Username(label Username)
now I want to compare those values enter by the user above to the table Trader, to check if the values match, how do I go about doing that??
here is as far as I got:
// Specify SQL Server-specific connection string
SqlConnection thisConnection = new SqlConnection(....)
// Open Connection
thisConnection.Open()
// Create comand for this connection
SqlCommand thisCommand = thisConnection.CreateCommand();
// Specify SQL query for this command
thisCommand.CommandText = "SELECT UserName, Password from Traders"
// Execute thisReader for specified command
SqlDataReader thisReader = thisCommand.ExecuteReader()
// While there are row to read
while (thisReader.Read())
{
What do I do here? how do I programatically compare my values taken from
from the user(via the C# Form - UserName / Password to the values stored
in the table that I want to compare with? All the examples I can find
output the values via Console.WriteLine()??
I hope this is not to long!
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You might find it better and more efficient to plug those values into the query rather than get everything in the table and compare them on the client end.
SELECT COUNT(*) FROM Traders WHERE UserName = @UserName AND Password = @Password
You then add Parameters to the command for @UserName and @Password
Then you can use:
int count = (int)thisCommand.ExecuteScalar();
A value of 0 indicates no match, or 1 indicates a match. If the value is anything else your database contains duplicated UserName/Password combinations.
Does this help?
"If a man empties his purse into his head, no man can take it away from him, for an investment in knowledge pays the best interest." -- Joseph E. O'Donnell
Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!
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Thanks, its less complicated than I thought it would be!
Regards,
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Hi,
can someone help me before I or my coputer go throw the window.
I'm trying to make a console VB.Net program that need to access to a SQL Server.
The console run on computer A and the SQL Server on computer B.
Everytime I try to open the sqlconnection or the oledbconnection, I'va got an error about system.security.permissions or something like this.
So can any1 give me a little code that can just do what I want.
Regards
Sybux
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whether it is console app or web app or win app, connecting to sql server is gonna be same. check your connection string
Bhaskara
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I'm sure about my connectionString "server=myserver;userID=sqluser;password=itspassword"
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i think you are missing Database. When the user is created in SQL Server, we can setup the default db also. If you dont, it will be 'MASTER' db. I think that is why you get Permission error. Include database also in the connection string.
Bhaskara
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A sample of your code would be helpful. Your connection string is missing the database name "Data Source = 'Server Name';Initial Catalog = 'Database name';User =;Password ="....
Is the server set up for mixed/SQL security? if not this will fail...
Power corrupts and PowerPoint corrupts absolutely. - Vint Cerf
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Hi,
here is my connect code :
<br />
Dim cObjConn As SqlClient.SqlConnection<br />
cObjConn = New SqlClient.SqlConnection("Initial Catalog=myCatalog;UID=:) ; Password=:((;Data Source=MySQLServer")<br />
cObjConn.Open()<br />
And I still got the error
type System.Data.SqlClient.SqlClientPermission, System.Data, Version=1.0.5000.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089.
at System.Security.CodeAccessSecurityEngine.CheckHelper(PermissionSet granted
Set, PermissionSet deniedSet, CodeAccessPermission demand, PermissionToken permT
oken)
at System.Security.CodeAccessSecurityEngine.Check(PermissionToken permToken,
CodeAccessPermission demand, StackCrawlMark& stackMark, Int32 checkFrames, Int32
unrestrictedOverride)
at System.Security.CodeAccessSecurityEngine.Check(CodeAccessPermission cap, S
tackCrawlMark& stackMark)
at System.Security.CodeAccessPermission.Demand()
at System.Data.SqlClient.SqlConnectionString.Demand(SqlConnectionString const
r)
at System.Data.SqlClient.SqlConnection.Open()
type System.Data.SqlClient.SqlClientPermission, System.Data, Version=1.0.5000.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089.
at System.Security.CodeAccessSecurityEngine.CheckHelper(PermissionSet granted
Set, PermissionSet deniedSet, CodeAccessPermission demand, PermissionToken permT
oken)
at System.Security.CodeAccessSecurityEngine.Check(PermissionToken permToken,
CodeAccessPermission demand, StackCrawlMark& stackMark, Int32 checkFrames, Int32
unrestrictedOverride)
at System.Security.CodeAccessSecurityEngine.Check(CodeAccessPermission cap, S
tackCrawlMark& stackMark)
at System.Security.CodeAccessPermission.Demand()
at System.Data.SqlClient.SqlConnectionString.Demand(SqlConnectionString const
r)
at System.Data.SqlClient.SqlConnection.Open()
I really don't where I'm wrong. I'm using the same connection string in an ASP application which is also running on another computer than the sqlserver and all is ok for it ???
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I've found the error.
It wasn't in the connection string.
The fact was that I was running my application from a network drive and it seems that permissions are not the same.
Solution : run all from local hard drive !
Sybux is now happy
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I've inherited a somewhat old system with a large number of SQL queries. In a number of these queries, there are SELECTs within INNER JOINs. For example, here are two INNER JOINs that are part of the same query:
INNER JOIN
( SELECT * FROM Schema_types
) Schema_types ON Schema_types.Schema_typeID = Schemas.Schema_typeID
INNER JOIN
( SELECT * FROM Marketeers WHERE MarketeerID = 7
) Marketeers ON Marketeers.MarketeerID = Shipments.MarketeerID
This looks rather peculiar to me. Is there merit in doing it this way, or is this just wrong?
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This does look peculiar. It may have been the result of never cleaning up after intial development. I don't know any benefit of writing them this way. There may not be any benefit in cleaning them up - except for readablity.
INNER JOIN
Schema_Types
ON (Schema_types.Schema_typeID = Schemas.Schema_typeID)
INNER JOIN
Marketeers
ON ((Marketeers.MarketeerID = Shipments.MarketeerID) AND
(MarketeerID = 7))
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Using subqueries (the SELECT statements you speak of) in INNER JOINS can be very useful. However, here it looks stupid because it is just doing a SELECT * FROM... and I guess this would be sub-optimal because it has to create an internal set of data for the subquery that contains every field and they may not all be used once the data gets into the main query.
It would be better to do:
INNER JOIN Schema_types ON Schema_types.Schema_typeID = Schemas.Schema_typeID
INNER JOIN Marketeers ON Marketeers.MarketeerID = Shipments.MarketeerID
If my understanding of the query optimiser is correct then this should also speed up your query.
"If a man empties his purse into his head, no man can take it away from him, for an investment in knowledge pays the best interest." -- Joseph E. O'Donnell
Can't manage to P/Invoke that Win32 API in .NET? Why not do interop the wiki way!
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plz tell me as early as possible that how to bind a report with dataset of sql password protected database at runtime.
it is urgently required
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