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Hi
MySQL stores database files in the data folder specified in the configuration file.
But I want to use different location when creating new databases.
Is this possible ? And How ?
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I want to create an Access database on my PocketPC (WinCE4.2, PocketPC 2003 OS). Then using C# to populate tables, query tables, ...
From a simple search on Google.com I find that I must use ADOCE.NET but I didn't succeed to download it and also didn't see any control that I can use from Visual Studio 2003 (I created a project for Smart Mobile Device).
Is there any one has experiences doing such kind of work?
Best regards,
A. Riazi
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This is part of Platform Builder 3.0 and if you have not it, the setup will fail.
A. Riazi
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Hello all,
I made a database on the deployment server and i made some changes in the development server on the database struction releation data types etc...
the database on the deployment server filled with data.
how can i apply the changes from the develpement server on the deployment server without wast the data.
Regards,
Hay
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Create deployment scripts.
Take a copy of the production database (what you are calling the deployment server). Back up the production database and restore it to a test environment. e.g. a second SQL server instance on your development machine.
Write scripts that change the data model and run it on the copy. You may have to do this several times to get the scripts right so they don't fail.
Once you have written and debugged the change scripts you can run them on the production system.
As a general note, you should think about how to deploy changes to a database before making the changes. The first thing I do is to create the change scripts and repeatedly test them as development progresses so that I don't have any nasty surprises at the end. Also, because the restore process can be lengthy it means that will your test environment is restoring in the background you can do other development.
Does this help?
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Thanks so much ,
yes it is very helpful but i did the changes in the database how can i make script from the changes only.
Regards
Hay
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When you make changes in "the database" (by that I'm assuming you actually mean you used the Enterprise Manager") all that is happening is that the application is creating SQL scripts and running them.
All you need to do is to write scripts based on that. Enterprise manager can help by creating scripts for you. This will be a good starting point if you've created new tables, but you can take these scripts and modify them for just the changes.
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Thanks Colin i aprictiat your replyes .
I am useing Enterprise Manager but the script from the it for all database not for my chages only. and modifyed the hole script or take parties from it so hard if the database is large do you know any way we can do that.
I thinking about make new database with the new chages and make a database maping to transfer the data from the old database to the new database.What do you think?
Regares,
Hay
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In Enterprise manager,
1)Right click on the table you wish to alter.
2)Right click and choose Design Table.
3)As soon as you make a change, a "Save Change script" Icon on the toolbar becomes active.
This will allow you to save your changes to a text file.
hth
Gregg
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Hi,
I'm using the ATL OLEDB classes and I get the following error:
"Multiple-step OLE DB operation generated errors. Check each OLE DB status value, if available. No work was done."
when I query the database with a query that uses the "DISTINCT" keyword. Here is a sample of my code.
<br />
HRESULT hr;<br />
CDataSource ds;<br />
CSession session;<br />
CCommand<CDynamicAccessor, CRowset> myAccessor;<br />
<br />
CComBSTR bstrUser(strUserId);<br />
CComBSTR bstrPassword(strPasswd);<br />
CComBSTR bstrServer(strSvrName);<br />
CComBSTR bstrDatabase(strDbName);<br />
<br />
CDBPropSet dbinit(DBPROPSET_DBINIT);<br />
dbinit.AddProperty(DBPROP_AUTH_PASSWORD, bstrPassword);<br />
dbinit.AddProperty(DBPROP_AUTH_PERSIST_SENSITIVE_AUTHINFO, false);<br />
dbinit.AddProperty(DBPROP_AUTH_USERID, bstrUser);<br />
dbinit.AddProperty(DBPROP_INIT_CATALOG, bstrDatabase);<br />
dbinit.AddProperty(DBPROP_INIT_DATASOURCE, bstrServer);<br />
<br />
hr = ds.Open(_T("SQLOLEDB"), &dbinit);<br />
<br />
if ( SUCCEEDED(hr) )<br />
{<br />
hr = session.Open(ds);<br />
}<br />
else<br />
{<br />
session.Close();<br />
ds.Close();<br />
exit(1);<br />
}<br />
<br />
CDBPropSet propset(DBPROPSET_ROWSET);<br />
propset.AddProperty(DBPROP_IRowsetChange, true);<br />
propset.AddProperty(DBPROP_IRowsetScroll, true);<br />
propset.AddProperty(DBPROP_CANFETCHBACKWARDS, true);<br />
propset.AddProperty(DBPROP_UPDATABILITY, <br />
DBPROPVAL_UP_CHANGE | DBPROPVAL_UP_INSERT | DBPROPVAL_UP_DELETE );<br />
<br />
char Query[] = "select distinct dl_num from deal"<br />
LONG lRowsAffected = 0;<br />
<br />
hr = myAccessor.Open(m_session, Query, &propset, lRowsAffected);<br />
If I remove the DISTINCT keyword, the query works fine 
Are there some things I need to set for the DISTINCT and GROUP BY keywords to work? We are using SQL Server 2000. Thanks for your help.
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Hi,
I am trying to find an article that clearly explains the various joins in the DataBases Can any one give me the link that explains well about these.
Thanking you in advance,
Satish.
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Lets say you have 2 tables A and B which cotains the following data
A B
-- --
1 1
2 2
4 3
6 4
7 5
8 6
An INNER JOIN will only match rows from two tables where the join condition matches on BOTH sides of the join.
SELECT * FROM A INNER JOIN B ON A.A = B.B
A B
----
1 1
2 2
4 4
6 6
A LEFT OUTER JOIN will return everything on the left side and the matches on the right side leaving nulls if there is no match
SELECT * FROM A LEFT OUTER JOIN ON A.A = B.B
A B
------
1 1
2 2
4 4
6 6
7 null
8 null
A RIGHT OUTER JOIN is similar but it will return everything on the right side and the matches on the left side leaving nulls if there is no match
SELECT * FROM A RIGHT OUTER JOIN ON A.A = B.B
A B
-------
1 1
2 2
null 3
4 4
null 5
6 6
A FULL OUTER JOIN returns everything on both sides leaving nulls if there is no match
SELECT * FROM A FULL OUTER JOIN ON A.A = B.B
A B
-------
1 1
2 2
null 3
4 4
null 5
6 6
7 null
8 null
Does this help you see the patterns that are created by these join types?
DISCLAIMER: I created these results from my head. There may be errors
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hi Colin Angus,
Thank you very much for the explanation.It is very clear.I heard of few more joins that are equi join,self join Under what category does this belong to and what are they.
Thank you in advance,
Satish.
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A self join is just when you join a table onto itself. There is no special types of join.
Consider a table with a primary key, PK, and a foreign key, FK, and the foreign key refers to the primary key of a different row in the same table.
For instance:
PK FK
-------
1 3
2 3
3 7
4 7
5 8
6 3
7 null
8 null Now, do a join onto itself like this:
SELECT * FROM table AS t1 INNER JOIN table AS t2 ON t1.fk = t2.pk
t1.PK t1.FK t2.PK t2.FK
------------------------
1 3 3 7
2 3 3 7
3 7 7 null
4 7 7 null
5 8 8 null
6 3 3 7
Remember that t1 and t2 are actually the same table, you need the aliases so you can treat the table as if it were actually two separate tables. Once you have the aliased, you can do any type of join you like that you could on two separate tables. Also, thinking about it as being two separate tables, that happen to both hold exactly the same data makes it easier to comprehend.
Does this help?
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i get sintax error in this query, why?
query = "UPDATE TmyTable SET Title = '" + labelTitle.Text + "', Text = '" + TextBox1.Text + "', Left = " + this.Left + ", Top = " + this.Top + ", Color = " + panelColor.BackColor.ToArgb() + " WHERE ID = " + id;
the table is made:
[id][title][text][timer][info][Left][Top][Color]
counter | string | string | date | string | int | int | long
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Thanks for your advances, i've tried to remove that row but i get the same error also for the other two int value i try to insert, anyway that is the error message:
---------------------------
---------------------------
System.Data.OleDb.OleDbException: Syntax error into UPDATE statement
at System.Data.OleDb.OleDbCommand.ExecuteCommandTextErrorHandling(Int32 hr)
at System.Data.OleDb.OleDbCommand.ExecuteCommandTextForSingleResult(tagDBPARAMS dbParams, Object& executeResult)
at System.Data.OleDb.OleDbCommand.ExecuteCommandText(Object& executeResult)
at System.Data.OleDb.OleDbCommand.ExecuteCommand(CommandBehavior behavior, Object& executeResult)
at System.Data.OleDb.OleDbCommand.ExecuteReaderInternal(CommandBehavior behavior, String method)
at System.Data.OleDb.OleDbCommand.ExecuteNonQuery()
at note.nota.nota_Closing(Object sender, CancelEventArgs e) in c:\..\visual studio projects\...\file.cs:line 627
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Colin just told you and I had told you before in some threads below: use parametized queries. You don't have to think about how to format parameters, and also is more secure. Try this code:
string sql = "UPDATE TmyTable SET Title=@Title, Text=@Text," +
" Left=@Left, Top=@Top, Color=@Color WHERE ID=@ID";
SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Parameters.Add("@Title", labelTitle.Text);
cmd.Parameters.Add("@Text", TextBox1.Text);
cmd.Parameters.Add("@Left", this.Left);
cmd.Parameters.Add("@Top", this.Top);
cmd.Parameters.Add("@Color", panelColor.BackColor.ToArgg());
cmd.Parameters.Add("@ID", id);
cmd.ExecuteNonQuery();Do you see how you don't have to think about enclosing strings in single quotes or if day or month goes first in a date?
The above code is for SQL Server, which uses named parameters. OleDb* classes (Access for example) use unnamed parameters. In the query you just put a question mark, and add parameters to the Parameters collection in the order they appear in the query.
string sql = "UPDATE TmyTable SET Title= ?, Text= ?," +
" Left=@ ?, Top= ?, Color= ? WHERE ID= ?";
OleDbCommand cmd = new OleDbCommand(sql, conn);
cmd.Parameters.Add("@Title", labelTitle.Text);
cmd.Parameters.Add("@Text", TextBox1.Text);
cmd.Parameters.Add("@Left", this.Left);
cmd.Parameters.Add("@Top", this.Top);
cmd.Parameters.Add("@Color", panelColor.BackColor.ToArgg());
cmd.Parameters.Add("@ID", id);
cmd.ExecuteNonQuery();Oracle also uses named parameters like SQL Server. You have to prepend a colon in the query like in UPDATE TmyTable SET Title=:title, but not when adding the parameter: cmd.Parameters.Add("title", labelTitle.Text). If you are using some other database (mySql for example), search the docs, it's possible and parametized queries will make your life much easier (really!!)
-- LuisR
Luis Alonso Ramos
Intelectix - Chihuahua, Mexico
Not much here: My CP Blog!
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Thanks for all that you have told me i've used that code and runned the debug but i get the same error.
Maybe it depend by other things about database i don't know... 
What could it depend by?
it works if i don't save left, top and color values.
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i add i get this error only if i try to insert no string value within no string field.
Why i get error if i try to update integer or datetime field while for string i have no problem?
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Maybe the type of the column in the table you are trying to modify is set to varchar instead of int or datetime. Could you give us your table definition?
-- LuisR
Luis Alonso Ramos
Intelectix - Chihuahua, Mexico
Not much here: My CP Blog!
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i've just wrote it in my first post, anyway it is so:
the table is made:
[id][title][text][timer][info][Left][Top][Color]
counter | string | string | date | string | int | int | long
i get errors when i try to update 4-6-7-8
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I'm not sure about all of them, but some are SQL reserved words... for example Top. In your UPDATE statement, try encolosing each column name in brackets.
UPDATE table SET [Date]=@Date Good luck!
-- LuisR
Luis Alonso Ramos
Intelectix - Chihuahua, Mexico
Not much here: My CP Blog!
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nothing to do... i don't know really where i wrong!
i know it is a simple thing, but i don't know where is the error, i've tried also to rename the columns name, the parameters name, but nothing!!!
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