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Archive for the ‘Database’ Category

SQL Server 2005 : Access Tables / Entities across Servers.

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Accessing objects (tables..) across servers (SQL Server) is very simple.

Step 1: Create a link between two servers

Goto Query Window

EXEC sp_addlinkedserver
   'PRODSVR',
   N'SQL Server'
GO

‘PRODSVR’  is the name of the Server.Execute it.

Step 2: Setup Permission between Servers.In Management StudioGotoServer Object >> Linked Servers >>

PRODSVR (See Image)

Linked Servers List

Right Click on PRODSVR goto Properties and make changes as given below.

1-general.jpg

2-security.jpg

 3-securityoptions.jpg

Step 3: To access the tables in other server

Use the following  hirearchy

PRODSVR.dbname.dbo.tablename

To access Person.Address table from AdventureWorks database


Select * From PRODSVR.AdventureWorks.Person.Address

Advantages :


1. Update Production server with data from development server. (SSIS is alternate way)


2. Allow users to access production database without multiple logins. (windows authentication or SQL authentication) 



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Written by gchandra

February 18, 2008 at 3:31 pm

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'

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

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 , , ,

Retrieving the First N Records from a SQL Query

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3 Techniques

1. Simple Fixed ‘N’

SELECT TOP 10 NewsURL, ArticleTitle, ArticleAuthor
FROM NewsStoriesTable
ORDER BY PublicationDate DESC

2. Dynamic ‘N’ Records

CREATE PROCEDURE getRecentArticles
(
@ResultCount int
)
AS

Declare @sSQL

Set @sSQL = “Select TOP ” + @ResultCount + ” NewsURL, ArticleTitle, ArticleAuthor
FROM NewsStoriesTable ORDER BY PublicationDate DESC”

sp_executesql @sSQL

3. Dynamic ‘N’ Records (My Preferred way)

CREATE PROCEDURE getRecentArticles
(
@ResultCount int
)
AS

SET ROWCOUNT @ResultCount — KEY LINE WHICH DOES THE MAGIC

SELECT NewsURL, ArticleTitle, ArticleAuthor
FROM NewsStoriesTable
ORDER BY PublicationDate DESC

Written by gchandra

May 16, 2006 at 3:29 pm

Posted in Database

SQL2000 : Drop Database Contents from Query Analyzer

with one comment

U : Table
P : SP
PK : Primary Key
UQ : Unique Constraint
F : Foreign Key
FN : Functions
D : Default

To see the list of User Create Items
— SELECT * FROM sysObjects WHERE xType in (‘U’,’P’,’PK’,’UQ’,’F’,’FN’,’D’)

— Declare @sql NVarChar(4000)– Select @sql= isnull(@sql,”) +’Drop Table ‘ + Name + ‘;’ From sysObjects Where xType=’U’– Exec sp_executesql @sql

— Declare @sql NVarChar(4000)– Select @sql= isnull(@sql,”) +’Drop Proc ‘ + Name + ‘;’ From sysObjects Where xType=’P’– Exec sp_executesql @sql

— Declare @sql NVarChar(4000)– Select @sql= isnull(@sql,”) +’Drop Function ‘ + Name + ‘;’ From sysObjects Where xType=’FN’– Exec sp_executesql @sql

Written by gchandra

February 15, 2006 at 5:27 pm

Posted in Database