Saturday, 16 November 2013

SQL SERVER - Notes 7



49. Usage of Rule .
       Rule is a object which is used to specify a column acceptable values.
     
CREATE TABLE countries(NAME VARCHAR(3),code INT)
go

CREATE RULE countryrule AS @con IN ('US','IND')
go
EXEC sys.sp_bindrule 'countryrule', -- nvarchar(776)
   'dbo.countries.name' -- nvarchar(776)
   
go

INSERT INTO countries(name ,code)
VALUES ('Ind',545)
INSERT INTO countries(name ,code)
VALUES ('US',545)
INSERT INTO countries(name ,code)
VALUES ('UK',545)

EXEC sys.sp_unbindrule 'countryrule'

Note : This feature will be removed from the microsoft in the future release,so avoid this feature in the development work, Modify the feature
with check constraint.

Example
ALTER TABLE countries
ADD CONSTRAINT countryrule CHECK(name IN ('IND','US','UK'))


50. Usage of  sp_xml_preparedocument ?
            It reads the input xml and parsed the text using the MSXML Parser and returns the handle for the parsed document. this handle is valid for the duration of session or until the invalidated of handle using the sp_xml_removedocument

A Paresed document is stored internal cache of SQL SERVER. MSXML uses 1/8 of the total memory available for  the SQL SERVER.\


-- Save the xml document in the Cache of the Sql Server  ?
DECLARE @xmlstring VARCHAR(2000)
DECLARE @handle INT

SELECT @xmlstring = N'<Persons><Person><name>AB</name><age>25</age></Person><Person><name>Bc</name><age>26</age></Person></Persons>'
EXEC sys.sp_xml_preparedocument @handle OUTPUT,@xmlstring
SELECT * FROM OPENXML(@handle,'Persons/Person')
WITH (USERNAME  VARCHAR(40) 'name',age INT 'age')

EXEC sys.sp_xml_removedocument @handle


51. New Features available in SQL SERVER 2008 ?
  •       New DataType [Date, time, FileStream] 
         DECLARE @date DATE
         DECLARE @time TIME
  •       Compouned Operations [+=,-=,*=,/=]                
         DECLARE @i INT = 1
         SELECT @i+=2
         SELECT @i
  •       Merge Statement  
MERGE INTO [targettable] AS t
USING [sourcetable] AS s
ON t.[column] = s.[column]
WHEN MATCHED THEN
-- statements
WHEN NOT MATCHED THEN
-- statements
  •       Sparse Columns
  •       Table value parameters
  •       Integrated Full Text search
  •       Intellisense
  •       Transparent Data Encryption (Encrypt whole database explicitly)
  •       Resource Governor
  •       Policy Based Management
  •       Linq

52. What is sparse columns ?
         A Sparse column is a optimised storage format to store NULL values, we can specify a table column as sparse by SPARSE attribute. 

  •  It greatly reduces the space requirement for your table columns.
  • It doesn't take up any space when the column value contains the NULL.
  • It takes up more space when column contains NON-NULL value
  • It is suitable for only the columns which have storage value NULL in large percentage. 

CREATE TABLE employeetable
(
 id      INT IDENTITY(1,1),
 NAME    VARCHAR(40),
 addres  VARCHAR(200),
 tempaddres VARCHAR(300) SPARSE
            )

53. How to modify the value in XML ?

       Now below example will explain you how to change the value of an Hr to tech in an xml first tag.    [1]  Refers the occurrence of first element. 

       Xml Format:
<Emps>
  <Emp dept="HR">a</Emp>
  <Emp dept="HR" />
  <Emp dept="tech">R</Emp>
</Emps>
  
DECLARE @employeedata XML
DECLARE @deletecondition VARCHAR(20) = 'HR'

--xml
SELECT @employeedata = N'<Emps><Emp dept="HR">a</Emp><Emp dept="HR"></Emp><Emp dept="tech">R</Emp></Emps>'

SET @employeedata.modify('replace value of (/Emps/Emp[@dept=("HR")]/@dept)[1] with "Tech"')
SELECT @employeedata

Output: 
<Emps>
  <Emp dept="Tech">a</Emp>
  <Emp dept="HR" />
  <Emp dept="tech">R</Emp>
           </Emps>

54. How to insert a new tag in existing XML ?
      Now we see how to insert an new element in the existing xml , in different positions.
      Xml format:
<Emps>
  <Emp dept="HR">a</Emp>
  <Emp dept="HR" />
  <Emp dept="tech">R</Emp>
</Emps>


DECLARE @employeedata XML
DECLARE @deletecondition VARCHAR(20) = 'HR'

--xml
SELECT @employeedata = N'<Emps><Emp dept="HR">a</Emp><Emp dept="HR"></Emp><Emp dept="tech">R</Emp></Emps>'

SELECT @employeedata


--Insertion
SET @employeedata.modify('insert <Emp>b</Emp>  as first into (/Emps)[1]')
-- or
SET @employeedata.modify('insert <Emp>b</Emp>  into (/Emps/Emp)[1]') -- insert as last tag
SELECT @employeedata

<Emps>
  <Emp>b<Emp>b</Emp></Emp>
  <Emp dept="HR">a</Emp>
  <Emp dept="HR" />
  <Emp dept="tech">R</Emp>
</Emps>


55. How to DELETE a Value from XML based on Condition ?
      Delete a element tag from the xml based on condition.


Xml format:
<Emps>
  <Emp dept="HR">a</Emp>
  <Emp dept="HR" />
  <Emp dept="tech">R</Emp>
</Emps>


DECLARE @employeedata XML
DECLARE @deletecondition VARCHAR(20) = 'HR'

--xml
SELECT @employeedata = N'<Emps><Emp dept="HR">a</Emp><Emp dept="HR"></Emp><Emp dept="tech">R</Emp></Emps>'

SELECT @employeedata


--Deletion
SET @employeedata.modify('delete (//Emps/Emp[@dept=sql:variable("@deletecondition")])') -- delete all HR records
SET @employeedata.modify('delete (//Emps/Emp[@dept=sql:variable("@deletecondition")])[1]') -- delete first HR record

SELECT @employeedata

Output:

<Emps>
  <Emp dept="tech">R</Emp>
</Emps>

56. How to find the existence of a value or tag in XML ?
       Execute a two different code , based on occurrence of value in element

--Exist
IF @employeedata.exist('(/Emps/Emp[@dept="HR"])[1]') = 1
BEGIN
  SELECT 'Employee Exist in HR dept'
END
ELSE
BEGIN
      SELECT 'No employee exist in HR Dept'
            END









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