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Dim connection As OLEDBConnection = New OleDBConnection(strConnection)
Dim command As OledbCommand = New OleDbCommand("select * from table",connection)
connection.Open()
dtGrid.DataSource = command.ExecuteReader()
dtGrid.Bind()
Learning and Working
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Hi everybody!
I'm new to ADO and I want to create an MFC Application using ADO for my database manipulation. So I started with an easy example.
In the example, I need to write:
#import "c:\Program Files\Common Files\System\ado\mmado15.dll" no_namespace
rename("EOF", "EndOfFile")
But that doesn't work! I have a error tolding me that WS.NET cannot find msado15.dll.
So I looked at my path and make a research for it and I realize that msado15.dll do not exist.
So where can I find it?
thanks for helping.
Everything's beautiful if you look at it long enough...
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Your example has msado15.dll mispelled. Try this:
#import "c:\Program Files\Common Files\System\ADO\msado15.dll" \
no_namespace rename("EOF", "EndOfFile")
Darrell Long
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msado15.dll is part of the MDAC[^] run-time.
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Hi, all:
I am totally stuck, please help. I have a datagrid on the WinForm ( using C# ). I am trying to create a combobox for one of the columns. I use the technique described in MS KB Article 323167 ( coded in VB.NET) and I port the code to C#. It works fine for the existing rows. Whe I click on the * row ( i.e., try to create a new row) on the datagrid. The combobox seems there, but when I click on the down arrow, the combobox does not dropdown. Occasionally, I can get the dropdown, but when I leave the cell, the changed value goes to the previous row ( strange!). The primary key is AutoNumber, when I click on the new row ( with "*" in front of it), I sometime get little pencil in front of the row, but sometimes I do not get it except the autonumber ( almost like it does not treat as a new row ).
Has anyone use this combobox technique and work on the new row successfully? I include the code snippet ( handling the events) here, if you can spot anything I did wrong, please let me know.
Any help is highly appreciated. Thanks in advance.
Dion
************ Code Starts here ***********
private void dataGrid1_Paint(object sender, System.Windows.Forms.PaintEventArgs e)<br />
{<br />
if ( dataGrid1.CurrentCell.ColumnNumber == 1 )<br />
{<br />
cbType.Width = dataGrid1.GetCurrentCellBounds().Width;<br />
}<br />
}<br />
<br />
private void dataGrid1_CurrentCellChanged(object sender, System.EventArgs e)<br />
{<br />
if ( dataGrid1.CurrentCell.ColumnNumber == 1 )<br />
{<br />
cbType.Visible = false;<br />
cbType.Width = 0;<br />
cbType.Left = dataGrid1.GetCurrentCellBounds().Left;<br />
cbType.Top = dataGrid1.GetCurrentCellBounds().Top;<br />
cbType.Text = dataGrid1[dataGrid1.CurrentCell].ToString() + "";<br />
cbType.Visible = true;<br />
}<br />
else<br />
{<br />
cbType.Visible = false;<br />
cbType.Width = 0;<br />
} <br />
}<br />
<br />
private void dataGrid1_Scroll(object sender, System.EventArgs e)<br />
{<br />
cbType.Visible = false;<br />
cbType.Width = 0;<br />
}<br />
<br />
<br />
private void dataGrid1_Click(object sender, System.EventArgs e)<br />
{<br />
cbType.Visible = false;<br />
cbType.Width = 0;<br />
}<br />
<br />
<br />
private void cbType_TextChanged(object sender, System.EventArgs e)<br />
{<br />
if ( dataGrid1.CurrentCell.ColumnNumber == 1 )<br />
{<br />
cbType.Visible = false;<br />
<br />
if ( ( dataGrid1[dataGrid1.CurrentCell] + "") == "" )<br />
{<br />
SendKeys.Send("*");<br />
}<br />
<br />
dataGrid1[dataGrid1.CurrentCell] = cbType.Text;<br />
} <br />
}
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i tried to add records to my database table but cant due to foreign key problem.. how do i solve tat?
i tried deleting all the relationships and i was able to add successfully but not when i add in the relationships.
2 tables involved:
tblcompany
- accountnumber (primary key)
- companyname
- address
tblcustomer
- customerid (primary key, auto generated)
- companyname [foreign key]
- username
- password
- name
- contactnumber
are these tables linked correctly? can someone help? thanks in advance
Laine
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Using string fields as keys is most of the time A Bad Idea.
Its not really clear from your table synopsis which is the "parent" and which is the "child" in your data logic. So i'll ignore what you've done and use a fictional example.
tblCompanies
------------
CompanyId (primary key, autonumber)
CompanyName
CompanyAddress
Company PhoneNumber
tblEmployees
------------
EmployeeId (primary key, autonumber)
CompanyId (foreign key)
EmployeeName
EmployeeInsideLegMeasurement
I hope that example makes it more clear.
#include <beer.h>
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thanks for ur reply jon.. the company table is the parent and the customer/employee table is the child.
the company data muz exist before the employee can sign up to be a member..
the data field for the companyID is alphanumeric.. and employees have problem remembering their company account number.. that's why i choose that they enter their company name instead.. this is to identify which employee from which company logs on.
any idea on how to go about designing a better database than the one i did earlier? any comments, suggestions will be deeply appreciated.. 
Laine
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If you wanna make so that the employees enter alphanumeric strings, why don't you make a column with that and an ID column for key?
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First of all:
1. What DB do you use? Oracle, SQL-Server, Access, DB2?
2. Post your error message (or error code)
3. Post your table-definitons
4. Post the INSERTs you tried.
Some things you should check:
1. Most DBs are case sensitive. So 'comp1' != 'Comp1' => master-key won't be found
2. Even if it sounds silly -> Check for typing errors!
3. Be sure to create a company before creating a customer for it.
4. You can only delete a record from tblcompany if no record of tblcustomer is referencing to it.
The included example should work (assuming accountnumber, customerid and contactnumber to be NUMBERS, the others VARCHAR)
INSERT INTO tblcompany VALUES(1, 'comp1', 'someaddress');<br />
INSERT INTO tblcompany VALUES(2, 'comp2', 'someaddress');<br />
<br />
INSERT INTO tblcustomer (companyname, username, password, name, contactnumber) VALUES ('comp1', 'uname', '***', 'name', 1);
--
karl
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i am using sql server2000. when i try to add a record to the database, the following error occurred:
"INSERT statement conflicted with COLUMN FOREIGN KEY constraint 'FK_tblCustomer_tblCompany'. The conflict occurred in database 'myDatabase', table 'tblCompany', column 'accountnumber'. The statement has been terminated."
i am sure that all the spellings are correct and there are no typing mistakes anywhere.
the tables involved are:
tblcompany
- accountnumber (primary key) : varchar
- companyname : varchar
- address : varchar
tblcustomer
- customerid (primary key, auto generated) : int
- companyname [foreign key] : varchar
- username : varchar
- password : varchar
- name : varchar
- contactnumber : int
the parent would be tblcompany whereas the customer table as the child.
i am using a stored procedure:
ALTER Procedure AddCustomer
(
@CompanyName varchar(50),
@Username varchar(50),
@Password varchar(50),
@Name varchar(50),
@PhoneNo varchar(50)
)
AS
INSERT INTO tblCustomer
(CompanyName, Username, Password, Name, PhoneNo)
VALUES
(@CompanyName, @Username, @Password, @Name, @PhoneNo)
RETURN
this is how i call the stored procedure:
Public Sub processRegistration(ByVal sender As System.Object, ByVal e As System.EventArgs)
Dim CompanyName As String = txtCompany.Text
Dim Username As String = txtUsername.Text
Dim Password As String = txtPassword.Text
Dim Name As String = txtName.Text
Dim PhoneNo As String = txtContact.Text
Dim ocm As SqlClient.SqlCommand
ocm = New SqlClient.SqlCommand("AddCustomer", SqlConnection1)
ocm.CommandType = CommandType.StoredProcedure
Dim pcompanyname As SqlClient.SqlParameter
pcompanyname = New SqlClient.SqlParameter("@CompanyName", SqlDbType.VarChar, 50)
pcompanyname.Value = CompanyName
ocm.Parameters.Add(pcompanyname)
Dim pusername As SqlClient.SqlParameter
pusername = New SqlClient.SqlParameter("@Username", SqlDbType.VarChar, 50)
pusername.Value = Username
ocm.Parameters.Add(pusername)
.
.
SqlConnection1.Open()
ocm.ExecuteNonQuery()
SqlConnection1.Close()
End Sub
i have the company data in the tblcompany, but i juz couldnt add a customer to the customer table.
can anyone tell me wat is wrong?
Laine
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ylaine wrote:
tblcompany
- accountnumber (primary key) : varchar
- companyname : varchar
- address : varchar
tblcustomer
- customerid (primary key, auto generated) : int
- companyname [foreign key] : varchar
- username : varchar
- password : varchar
- name : varchar
- contactnumber : int
The foreign key in tblcustomer references to the PRIMARY KEY of tblcompany. So it references to accountnumber and not to companyname. If you want to set a foreign key to companyname you must define it as UNIQUE in tblcompany and change the fk-constraint to point to companyname.
--
karl
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ok.. got it.. thank you very much karl!;)
Laine
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Hiya I am just wondering if anyone has come across this problem.
I have an SQL database which I read and write to. I write a number of items( Number, Planet Name )the first time to the database fine. The items go in fine and in order into their columns:
e.g 1. Jupitar 2. Venus 3. Mars 4. Earth
Then when I modify the table in some way, e.g like deleting all the items, and refill the table with the exact same code, they come out in a different order e.g
3. Mars 1. Jupitar 4. Earth 2. Venus
And I definitely have not changed the code and they are all definitely deleted. WEIRD!! I have also done this with ACCESS database and works fine every time, only wrong in SQL.
Does anyone have any ideas on this??
grahamoj.
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don't cross post. waste of bandwidth.
#include <beer.h>
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I think that you're just stuck with the way it returns them to you unless you tell it *how* to return the records to you. ORDER BY is your friend. I'm assuming that your "Number" field is your identity field. Just order by that. Your query would then be:
SELECT Number, PlanetName FROM Planets ORDER BY Number
As long as you always add them in, in the same order, you should get them back in the same order when using the ORDER BY Number clause.
Hope this helps.
-Matt
------------------------------------------
The 3 great virtues of a programmer:
Laziness, Impatience, and Hubris.
--Larry Wall
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I can get a .doc inserted as a blob into the image type, but how do I get it out again and display it on a web page using C# ASP.net?
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I set up ABCUpload and got an image successfully saved to my database.
When you go into the database the image is stored as a long binary data.
When you click on it to open it , there is an error
there was a problem while Access was communicating with the OLE server or ActiveX Control. Close the OLE server and restart it outside of MS Access. Then try the original operation in Access again
How can I view the image- I need it to be stored in the database and not linked to it
Please help!!
Maria
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I would like to have a transaction which would lock a particular row in the table but leave the other available to other threads.
I tried:
set transaction isolation level serializable
....
select * from sometable with (rowlock, xlock) where ....
....
commit
I tried with 2 instances of query analyzer debugging and I realized that the lock was table-wide.
How do you make the lock row-wise.
tx
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The column in the WHERE needed an index.
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I am still kinda new at the database structuring stuff and I was looking for some more opinions.
Goal: to design an online inventory system, such that if I was to look up employee x I would see that he has computer Z containing video adapter y. Additionally I need to be able to look up employee x and see computer z contains windows 95. I would be nice to be able to limit the amount of information that I present to the web user, so that when he looks up employee x he sees just the basicis computer number, processor type, location, and OS type.
My thoughts:
<OL><br />
<Li>Have a list of employee that can have computer parts assigned to them.<br />
<li>Have a list of Objects that can be checked out.<br />
<li>Have a relationship between them so that one employee can have many Objects checked out.<br />
<li>Have a relationship between objects and itself so that one object can contain many other objects.<br />
</ol>
Here is where it becomes challenging, if two objects have a different set of properties(Like printers and mice) this schema would break down.
Question One Would it make sense to add these schemea chunks:
<OL><LI>A list of Properties that an object can obtain ( such as "DPI" or "mouseButtons")<LI>A relationship between Many properties and one object</OL>
This format would allow me to easily "drill down" but getting all of the information at once would be difficult...
Question Two Do you feel my Paradigm is right or wrong. How do you think I should reapproch this problem.
Question Three How would you approch this problem.
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It sounds to me like your thoughts are on the right track. I think that you would probably have to create a separate table for each asset type (e.g. computer chasis's, keyboards, mice, video cards, etc.). Then you can set up other tables to associate one asset with another (e.g. video card x is in computer y, etc.) Then you would finally set up a table that would assocate people (employees) to assets. Then you would have all of your data available. What you display to the user is up to you. Just because you have lots of data in your DB doesn't mean you have to show it all. With a fairly simple join, you could bring back a list of pertinent things that you want the user to see rather than everything.
I think the reason that you're not getting more responses on this question is because it is quite a daunting task to design such a system if you are to do it properly. It sounds like it would present a fun challenge, but It certainly isn't simple. I think you're on the right track, though.
Good luck.
-Matt
------------------------------------------
The 3 great virtues of a programmer:
Laziness, Impatience, and Hubris.
--Larry Wall
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If I use the OleDB provider i can access all sorts of automatic code generating bits in Visual Studio (c#). But if I use the ODBC provider I seem to have to hand code everything .Am I missing out on something ? is there some button I should have pushed , or are you on your own with the ODBC provider ? Even the OleDb provider for ODBC is not as good as other OleDb providers . Is it any better in the new Beta ?
Am I the only one forever playing catch up with technology , while all the juicy opportunites keep rolling by ?
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Hi
I have an access database with two tables.
First table is called custDetails with fields:
CustID and CustName
Second table is called UsageHistory with fields:
CustID, UsagePeriod, DlyAmount, MnthlyAmount, Total
How do i show the whole of UsageHistory table and just the custName field from CustDetails table on a datagrid using a dataview?
I know how to create a connection to the database and execute the SQL statement at the start, and how to bind the datagrid to the dataview at the end. It just seems to be the middle bits that I'm unsure of that's stuffing me up  ie - datasets, dataadapters and datatables. I can get my form to display the table usageHistory and all its fields on the datagrid. But when i try to add in the field custName to the datagrid that's when i have problems.
Anyhelp or any new block of code would be greatly appreciated.
Dim ds As DataSet = New DataSet()
Dim dv As New DataView()
Dim da As OleDbDataAdapter
Dim strConnection As String = _
"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\ClientInfo.mdb; Persist
Security Info=False"
Dim cn As OleDbConnection = New OleDbConnection(strConnection)
'Open a database connection.
cn.Open()
Dim strSql As String
strSql = "SELECT UsageHistory.*, CustDetails.CustName " & _
"FROM CustDetails INNER JOIN UsageHistory ON CustDetails.CustID " & _
"= UsageHistory.CustID;"
da = New OleDbDataAdapter(strSql, cn)
************This is the part that i'm unsure of*****
da.TableMappings.Add(?????)
' Fill the DataSet.
ds = New DataSet()
da.Fill(ds)
Dim dt As DataTable = ds.Tables.Add(???????)
*****************************************************
cn.Close()
'Make a DataView for the data.
dv = New DataView(dt)
'Bind the DataGrid control to the DataView.
dgUsage.DataSource = dv
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