"Data Isolation" Vs "Locking" - Database Discussion Boards

I want to add,delete,save my project ...

mostafa_h1-Sep-05 23:07

1-Sep-05 23:07

hi all
in my database application and in my form :
I use 2 table from SQL .In table1(mainTable) my fields are id_car,car,id_city .
and in Table2 my fields are id_city,city .
id_city in table1 has a relation to id_city in Table2 , but
I want to fill the Datagrid by table1 .
by the way I have a combobox for displaying the city by the the city field from table2 (from the relation exist
between two table )and ,I have a textbox for displaying the car and a datagrid contaning from city and car,in my form .

For displaying the records , I use a View in SQL .
because when I want to save and repeat one city in the some or more record , I select it by the id_city from the table2 .
Now I want to add,update,Delete my database application
in spite of that we know about the relation table1 and table2 .
ofcourse my main table in the application is the table1 .
thanks in advance!!!

mostafa hosseiny b.

Confused | :confused:

mostafa hosseiny b.

How will I know that DSN is not pointing to any database?

PrashantJ1-Sep-05 21:17

PrashantJ

1-Sep-05 21:17

Hi,

I have the following C++ code, using MS-studio.Net (MFC).

CDatabase aDatabase;
TCHAR buffer[400];
SQLRETURN rc = SQLGetInfo(aDatabase.m_hdbc, SQL_DATABASE_NAME,(SQLPOINTER buffer, sizeof(buffer), &size);

With this code at present, the value returned in buffer if "master" if the DSN is not pointing to any database. I think master is the default database.

I actually want to know if the DSN is pointing to a correct(existing) database or not. I wanted to display a message if the DSN is not pointing to any database or if its pointing to a database that no more exists.
How can I achieve this? Anybody any thoughts?

Thanks,
Joe

Re: How will I know that DSN is not pointing to any database?

Michael Potter2-Sep-05 5:25

Michael Potter

2-Sep-05 5:25

Ask for the schema:

SELECT TABLE_CATALOG 
FROM INFORMATION_SCHEMA.TABLES
GROUP BY TABLE_CATALOG

Look up INFORMATION_SCHEMA in BOL if you need to verify more than just the catalog (database) name.

Data Isolation and Transaction Isolation

devvvy1-Sep-05 17:37

devvvy

1-Sep-05 17:37

Hey guys,

QUESTION 1: Is this correct?

I. Transaction Isolation Level Serializable = Pessimistic Locking

For example:
trx = conn.BeginTransaction(IsolationLevel.Serializable)

ie. When two threads try to access the same record..

1.  Thread 1 begins tran and select [record 123] (I presume a X-lock *Exclusive lock* is acquired)<br />
2.  Thread 2 begins tran and *attemp* to select [record 123] (but must wait before select comes thru because Transaction Isolation is set to Serializable -- ie. pessimistic -- I presume Thread 2 is also trying to acquire X-lock at this time but need to wait)<br />
3. Thread 1 commit updates on [record 123]<br />
4. Thread 2 select on [record 123] comes thru <br />
5. Thread 2 update<br />
6. Thread 2 commits update<br />

II. Transaction Isolation Level = ??? For optimistic locking?

<br />
   1.  Thread 1 begins tran and select [record 123] (I presume a S-lock *shared lock* is acquired)<br />
   2.  Thread 2 begins tran and select [record 123] and it comes thru (Thread 2 also acquire a S-lock at this point)<br />
   3. Thread 1 commit updates on [record 123 \ file updated: firstname] (Thread 1 acquired a U-lock *update lock* at this point)<br />
   4. Thread 2 commit updates on [record 123 \ file updated: lastname] (CAUTION: firstname commited by Thread 1 overwritten by Thread 2 at this time) (Thread 2 acquired a U-lock *update lock* at this point)<br />

Is this correct?

QUESTION 2:
With cursor you get to specified locking, for example:

<br />
    Dim objRs As ADODB.Recordset<br />
    Set objRs = New ADODB.Recordset<br />
<br />
    Or Dim Objrs As New Adodb.Recordset<br />
<br />
    objRs.Open "users", objConn, adOpenKeyset, adLockOptimistic, adCmdTable

But how with ... "System.Data.IDbConnection"?

Thanks in advance.

-- modified at 23:37 Thursday 1st September, 2005

Re: Data Isolation and Transaction Isolation

airbus3801-Sep-05 22:14

airbus380

1-Sep-05 22:14

What DBMS you have ?
Level of isolation may differ from theory to a specific DBMS or
from a DBMS to another DBMS !

---
object oriented
uml oriented
iconix oriented
sql oriented
truespace oriented
---
solitare oriented Smile | :)

Re: Data Isolation and Transaction Isolation

devvvy1-Sep-05 22:21

devvvy

1-Sep-05 22:21

say, Microsoft SQL Server?

Re: Data Isolation and Transaction Isolation

airbus3802-Sep-05 0:42

airbus380

2-Sep-05 0:42

1) ok

2) Try use SQL Server SET command like this: SET TRANSACTION ISOLATION LEVEL SERIALIZABLE for example

---
object oriented
uml oriented
iconix oriented
sql oriented
truespace oriented
---
solitare oriented Smile | :)

"Data Isolation" Vs "Locking"

devvvy3-Sep-05 21:33

devvvy

3-Sep-05 21:33

No, there seems to be distinction between "Data Isolation (Serializable/Repeatable Read/Read Committed/Dirty)" and "Optimistic (or Pessimistic) Locking"...

In my post I was asking:

"Serializable" corresponds to "Pessimistic locking" --> Now, for "Optimistic locking", which level of data isolation does it correspond to? Repeatable Read?

Norman Fung

HOW I KNOW WHAT TABLES ARE IN A DATA BASE IN CSHARP

alonso2k811-Sep-05 10:40

alonso2k81

1-Sep-05 10:40

HOW I KNOW WHAT TABLES ARE IN A DATA BASE
PLEASE HELP ME.
I KNOW THE ARE A DATA BASE PRINCIPAL IN SQL SERVER WHIT CONTAINS ALL DATA BASE NAMES AND TABLES CONTAINS

Re: HOW I KNOW WHAT TABLES ARE IN A DATA BASE IN CSHARP

Michael P Butler1-Sep-05 11:21

Michael P Butler

1-Sep-05 11:21

try this[^]

Michael

CP Blog [^] Development Blog [^]

Re: HOW I KNOW WHAT TABLES ARE IN A DATA BASE IN CSHARP

Duncan Edwards Jones1-Sep-05 12:10

Duncan Edwards Jones

1-Sep-05 12:10

You could look in the table sysobjects (or this may be different if you are using a different database type)

'--8<------------------------
Ex Datis:
Duncan Jones
Merrion Computing Ltd

Re: HOW I KNOW WHAT TABLES ARE IN A DATA BASE IN CSHARP

Christian Graus1-Sep-05 15:30

Christian Graus

1-Sep-05 15:30

STOP YELLING !!!

Christian Graus - Microsoft MVP - C++

Re: HOW I KNOW WHAT TABLES ARE IN A DATA BASE IN CSHARP

miah alom2-Sep-05 4:59

miah alom

2-Sep-05 4:59

What is the database that you are using.
Assuming its SQL Server

To get an *approximate* count for all tables, you can use the following:

SELECT
[TableName] = so.name,
[RowCount] = MAX(si.rows)
FROM
sysobjects so,
sysindexes si
WHERE
so.xtype = 'U'
AND
si.id = OBJECT_ID(so.name)
GROUP BY
so.name
ORDER BY
2 DESC

Re: HOW I KNOW WHAT TABLES ARE IN A DATA BASE IN CSHARP

miah alom2-Sep-05 5:23

miah alom

2-Sep-05 5:23

SELECT
[TableName] = so.name,
FROM
sysobjects so
WHERE
so.xtype = 'U'
ORDER BY
so.name

group by and concat dependent rows

HELP_ME!!1-Sep-05 2:22

HELP_ME!!

1-Sep-05 2:22

got a problem:

table(with names A, B):

A B
----------
1 Hallo
1 wie geht es dir?
2 schlecht!
3 nein,
3 eigentlich gut!

I want the result:

A B Resultat C
-------------------------------------------
1----Hallo----------------
1----wie geht es dir?-----Hallo wie geht es dir?
2----schlecht!------------schlecht!
3----nein,----------------
3----eigentlich gut!------nein, eigentlich nicht

Thank`s for helping!!!

nico

Re: group by and concat dependent rows

airbus3801-Sep-05 3:03

airbus380

1-Sep-05 3:03

Try this:

First) You must create a "user defined function" (T SQL function)
like this

CREATE FUNCTION SSum (@a INT) //SSum = string sum
RETURNS NVARCHAR(255) AS
BEGIN

DECLARE @ssum NVARCHAR(255)
DECLARE @b NVARCHAR(25)
SET @ssum = ''

DECLARE crs CURSOR FOR SELECT B FROM table WHERE A = @a
OPEN crs

FETCH NEXT FROM crs INTO @b
WHILE( @@FETCH_STATUS = 0 )
BEGIN
SET @ssum = @ssum + '-' + @b
FETCH NEXT FROM crs INTO @b
END

CLOSE crs
DEALLOCATE crs

IF( LEN(@ssum) != 0 )
SET @ssum = SUBSTRING(@ssum,2,255)

RETURN @ssum

END

Second) Build a SELECT query using SSum function like this:

SELECT DISTINCT A , dbo.SSum(A) AS Result
FROM table

---
object oriented
uml oriented
iconix oriented
sql oriented
truespace oriented
---
solitare oriented Smile | :)

MDF files

cberam1-Sep-05 1:23

cberam

1-Sep-05 1:23

Hi,

I have .MDF ,SQL server DB files.

How to import those data or how to open .MDF files to the sql server or any other DB .

Pls help
Ram

Re: MDF files

airbus3801-Sep-05 2:20

airbus380

1-Sep-05 2:20

Just install a copy of SQL Server or MSDE and attach database files with sp_attach_db system stored procedure.

If you use MSDE and you don't have Enterpreise Manager you may use
osql or isql
commnad prompt tool.

object oriented
uml oriented
iconix oriented
sql oriented
truespace oriented
---
solitare oriented Smile | :)

triggers?

Soviet31-Aug-05 23:35

Soviet

31-Aug-05 23:35

hey i would like to "trigger" methods on a remote pc when my database changes(update occurs) the remote program is my GUI and the methods get the info from the database. How would i program this? would i need to write a smll app on the sql server and then let it some how call the remote methods or trigger them? please include code as i dont know anything. v new to coding in C#.

thanks

Re: triggers?

Anonymous1-Sep-05 11:23

Anonymous

1-Sep-05 11:23

You could create a SQL trigger (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_create2_7eeq.asp[^]) that invokes a COM component using sp_OACreate (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/tsqlref/ts_sp_oa-oz_9k2t.asp[^]) which invokes your remote methods.

Re: triggers?

jonathan151-Sep-05 22:54

jonathan15

1-Sep-05 22:54

Be carefull if using sp_OACreate to run a COM component. ActiveX dll's typically run in process which means they are running in the same memory as your database. A badly written dll is likely to corrupt memory in the SQL Server environment which could be containing some of your data. Although you can get it to run out of process it is not an easy thing to set up. An ActiveX.exe will run out of process by default.

Jon

Reg: MSOLAP (need to load custom data)

kuldeepjangir31-Aug-05 18:47

kuldeepjangir

31-Aug-05 18:47

Hello,

I am developing an application where I need to load custom data to Analysis Server (MS-OLAP) without going through any OLE DB

Provider. I am able to load data into dimensions/cubes using Microsoft OLE DB provider for ODBC Drivers. But my requirement is loading data at runtime from a buffer. Is there any way to do this? Are there any APIs which can help me to load this data directly?

Thanks & regards,

Is there example for Oracle connection?

rushing31-Aug-05 17:47

rushing

31-Aug-05 17:47

I found many articles in web and feel it is not clear for connect Oracle 9i later with .net framework 2.0 beta 2.
Some namespace like OracleClient could not be used,and new System.Data.Common does not have examples.
The ODP.NET seems need to download some libary.After downloading a lib writen at 2002, the vs.net 2005 does not has any change.
Could you show me some examples?
Thanks a lot!

Re: Is there example for Oracle connection?

Tigerkatze14-Sep-05 1:47

Tigerkatze

14-Sep-05 1:47

Hi!

One possibility is to use an oleDBConnector (using System.Data.OleDB).

OleDBConnection oleDdCon = new OleDbConnection("Provider=OraOLEDB.Oracle;Data Source=" + sDataSource + ";User ID=" + sUserID + "; Password=" + sPWD);
oleDBCon.Open();

-- modified at 7:49 Wednesday 14th September, 2005

Import data from Access into SQL Server 2005 Express

AesopTurtle31-Aug-05 16:22

AesopTurtle

31-Aug-05 16:22

Hi, I'm still new to sql server 2005 express integrated with VS.NET 2005 Beta 2. I'd like to import my data from Access into my newly created table in sql server 2005 express. How can I do so? Thank you so much.

KiT

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