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SQL Server, Clean your Database Records and reset Identity Columns, The Shortest Path

with 4 comments

(Copied from Moses’s Blog for my reference)

Well, I had a small issue regarding writing a script to clean a database we have and reset its identity columns in all tables. Although the database wasn’t huge one (less than 100 tables) I had to trace relations to be able to delete child table’s records before parent’s ones because of the foreign key constraints. The solution is disable the foreign keys and delete records with no fear of any errors then enables the constraints again.
Well, I found a solution to disable all constraints without the need to go on each table and disable it manually. and I was happy to know that I can use this solution in deleting all records from all tables. Not only this I was able to use the same solution to reset identity columns in all tables.

The solution was to use this built in stored procedure sp_MSforeachtable. For help about this proc search for it in Books online or use this sp_helptext sp_MSForeachtable.

Now back to my 6 lines, bellow is how I re-zeroed my Database:


1: /*Disable Constraints & Triggers*/
2: exec sp_MSforeachtable 'ALTER TABLE ? NOCHECK CONSTRAINT ALL'
3: exec sp_MSforeachtable 'ALTER TABLE ? DISABLE TRIGGER ALL'
4:
5: /*Perform delete operation on all table for cleanup*/
6: exec sp_MSforeachtable 'DELETE ?'
7:    
8: /*Enable Constraints & Triggers again*/
9: exec sp_MSforeachtable 'ALTER TABLE ? CHECK CONSTRAINT ALL'
10: exec sp_MSforeachtable 'ALTER TABLE ? ENABLE TRIGGER ALL'
11:   
12: /*Reset Identity on tables with identity column*/
13: exec sp_MSforeachtable 'IF OBJECTPROPERTY(OBJECT_ID(''?''), ''TableHasIdentity'') = 1 BEGIN DBCC CHECKIDENT (''?'',RESEED,0) END'

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Written by gchandra

February 18, 2008 at 10:23 am

Organize your SQL Server 2005 tables in a better way !!

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When you create tables in SQLServer (2005) by default its all get created under default schema. (dbo.)

If you have too many tables then the table list could be confusing / clumsy.

Here enters Schema

(see image)

Schema Example

To organize your tables into meaningful groups (or namespaces)

First create a schema

CREATE SCHEMA Person
GO

Then Alter your existing table

ALTER SCHEMA Lookup
TRANSFER dbo.Contact
GO

So now that you have grouped your tables into different schemas.

How to use them ? The usual way but with schema name added to it.

SELECT * FROM Person.Contact


What is Schema ? (from MSDN)Beginning in SQL Server 2005, each object belongs to a database schema. A database schema is a distinct namespace that is separate from a

database user.  Schemas can be created and altered in a database, and users can be granted access to a schema. A schema can be owned by any

user, and schema ownership is transferable.

In previous versions of SQL Server, database users and schemas were conceptually the same object. Beginning in SQL Server 2005, users and schemas

are separate, and schemas serve as containers of objects.

Written by gchandra

February 6, 2008 at 9:07 am

AJAX – Export to Excel / Word

with 17 comments

If you are using Update Panel and try to Export gridview contents to EXCEL or Word, your asp.net page will throw nasty error. “Sys.WebForms.PageRequestManagerParserErrorException”

Its because AJAX & Response.write don’t go together.  By calling Response.Write() directly you are bypassing the normal rendering mechanism of ASP.NET controls. The bits you write are going straight out to the client without further processing (well, mostly…). This means that UpdatePanel can’t encode the data in its special format.

There are couple of ways to solve this problem.

1. Place the Export Button outside of Update Panel.

2. By Pass the Export Button using <Triggers>

 </ContentTemplate>
        <Triggers>
            <asp:PostBackTrigger ControlID=”cmdExport” />
        </Triggers>

</asp:UpdatePanel>
if your Export button is part of UserControl then specify usercontrolid:buttonid

 </ContentTemplate>
        <Triggers>
            <asp:PostBackTrigger ControlID=”uscSelCtl:cmdExport” />
        </Triggers>
    </asp:UpdatePanel>

More Reading…

Written by gchandra

January 8, 2008 at 10:12 am

Asp.net Web Service Timing Out (0x80004005)

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Recently if your webservices started failing / timing out it its worth your time to take a look at this support article.

“HttpException (0x80004005): Request timed out.”

“System.InvalidOperationException: There were not enough free threads in the ThreadPool object to complete the operation”

 Contention, poor performance, and deadlocks when you make Web service requests from ASP.NET applications

http://support.microsoft.com/kb/821268

Related Reading :

Item 5 talks about Asp.Net WS

http://blogs.msdn.com/lucascan/archive/2008/01/06/lucascan-s-top-5-tips-for-a-healthy-asp-net-application.aspx

Written by gchandra

January 8, 2008 at 9:47 am

Asp.Net Filter Datatable by Column

with 6 comments

Filter Datatable by Rows

If you need to get subset of a big dataset into datatable Rowwise …


Dim dtEmp as DataTable
Dim dsEmployee as New DataSet

dsEmployee = someobject.getdata()  'dataset can be populated in many ways which is not explained here.

Dim sExpr as String
Dim drRows() as DataRow, drSingleRow as DataRow

sExpr = "EmpID > 100"  'Condition

drRows = dsEmployee.Tables(0).Select(sExpr)

'If you need to add Sort Order it can be added to sExpr

Dim sSortOrder as String
sSortOrder = "EmpName DESC"
drRows = dsEmployee.Tables(0).Select(sExpr,sSortOrder)

For Each drSingleRow in drRows
 dtEmp.ImportRow(drRows)
Next

' Datatable dtEmp has filtered records

Filter Datatable by Column

If you need to get subset of big dataset into datatable columnwise…


Dim dtEmp as DataTable
Dim dsEmployee as New DataSet

dsEmployoee = someobject.getdata()  'dataset can be populated in many ways which is not explained here.

'This copies the structure and data

dtEmp = dsEmployee.Tables(0).Copy

dtEmp.Columns.Remove("Unwanted Column 1")
dtEmp.Columns.Remove("Unwanted Column 2")
dtEmp.Columns.Remove("Unwanted Column 3")

Written by gchandra

January 7, 2008 at 4:13 pm

SQL Server 2005 : Verify table already exists

with 2 comments

Verifying that an object exists

If the table exists, it is deleted. If the table does not exist, the DROP TABLE statement is not executed.

IF OBJECT_ID (N’dbo.AWBuildVersion’, N’U’) IS NOT NULL
 DROP TABLE dbo.AWBuildVersion;
GO

Syntax :

OBJECT_ID (‘object_name’, [‘object_type’])

Object Type is optional, and possible values it can hold are.. (Items in bold are frequently used)

Object type:

AF = Aggregate function (CLR)

C = CHECK constraint

D = DEFAULT (constraint or stand-alone)

F = FOREIGN KEY constraint

PK = PRIMARY KEY constraint

P = SQL stored procedure

PC = Assembly (CLR) stored procedure

FN = SQL scalar function

FS = Assembly (CLR) scalar function

FT = Assembly (CLR) table-valued function

R = Rule (old-style, stand-alone)

RF = Replication-filter-procedure

SN = Synonym

SQ = Service queue

TA = Assembly (CLR) DML trigger

TR = SQL DML trigger

IF = SQL inlined table-valued function

TF = SQL table-valued-function

U = Table (user-defined)

UQ = UNIQUE constraint

V = View

X = Extended stored procedure

IT = Internal table

Written by gchandra

December 4, 2007 at 12:01 pm

Posted in Database

Tagged with , , ,

Prevent Session Timeout in Asp.net

with 17 comments

Prevent Session Timeout in Asp.net [VB]

ASP.Net 2.0 [VB]

Inspired by this article from Code Project. [Thanks Ach1lles ]


I slightly modified few things to work for VB and VS2005 environment. The code works perfect and I’m very happy with it.First I created a Module file and created this function.


Public Function KeepAlive() As String

        Dim int_MilliSecondsTimeOut As Integer = (HttpContext.Current.Session.Timeout * 60000) - 30000
        Dim sScript As New StringBuilder
        sScript.Append("<script type='text/javascript'>" & vbNewLine)
        'Number Of Reconnects
        sScript.Append("var count=0;" & vbNewLine)
        'Maximum reconnects Setting
        sScript.Append("var max = 6;" & vbNewLine)
        sScript.Append("function Reconnect(){" & vbNewLine)
        sScript.Append("count++;" & vbNewLine)
        sScript.Append("var d = new Date();" & vbNewLine)
        sScript.Append("var curr_hour = d.getHours();" & vbNewLine)
        sScript.Append("var curr_min = d.getMinutes();" & vbNewLine)
        sScript.Append("if (count < max){" & vbNewLine)
        sScript.Append("window.status = 'Refreshed ' + count.toString() + ' time(s) &#91;' + curr_hour + ':' + curr_min + '&#93;';" & vbNewLine)
        sScript.Append("var img = new Image(1,1);" & vbNewLine)
        sScript.Append("img.src = 'http://localhost/myapp/reconnect.aspx';" & vbNewLine)

        sScript.Append("}" & vbNewLine)
        sScript.Append("}" & vbNewLine)
        sScript.Append("window.setInterval('Reconnect()',")
        sScript.Append(int_MilliSecondsTimeOut.ToString() & "); //Set to length required" & vbNewLine)
        sScript.Append("</script>")

        KeepAlive = sScript.ToString
End Function

All this code does is, build a simple javascript function and its called from server side.The works like this,- Gets the current session timeout duration.
– Subtract 30 seconds from it and assign it to MilliSecondsTimeOut variable
– Create a Reconnect() javascript function
– Create a global variable with max value 6
– Get current hour and Min [just for displaying the last refresh time]
– Verify whether count is less than max value (ie 6)
– If so, change the window status with Text
– Create a dummy image and set reconnect.aspx url as its source [this way a call is made to server and it wont session timeout]Create a timer using window.setInterval and assign the MilliSecondsTimeOut value.
[this way this function is called 30 seconds before session timeout]Tha max value (6) can be set to any number. If its 6 then this session timeout is avoided 5 times.

Default session timeout is 20min. 20 * 5 = 100 mins. Which is good for non-secure page.

Then

On the pages where I want to prevent Session Timeout I entered this line.


Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Try
  'dont forget to add this line 
  Page.ClientScript.RegisterClientScriptBlock(Me.GetType, "reconn key", KeepAlive())
 
 If Not Page.IsPostBack Then
 ---
 ---
 ---
 End If

Catch eX as Exception
 '----
End Try
End Sub

Created reconnect.aspx in Visual Studio and deleted the .vb and .designer.vb files.This is the final version of reconnect.aspx


<%@ Page Language="vb" AutoEventWireup="false"%>
<%@ OutputCache Location="None" VaryByParam="None" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "<a href="http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" mce_href="http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd</a>">
<html xmlns="<a href="http://www.w3.org/1999/xhtml" mce_href="http://www.w3.org/1999/xhtml">http://www.w3.org/1999/xhtml</a>" >
</html>

Note : When you compile the project sometimes, VS2005 complains reconnect.aspx is not in right format.
So I EXCLUDED this file from my project. Now VS 2005 will compile without complaining and the logic will also work.- Happy Programming

Written by gchandra

November 26, 2007 at 3:42 pm