08 qmds2005 session11

Querying and Managing Data Using SQL Server 2005
Objectives

In this session, you will learn to:
Create and manage views
Implement a full-text search
Implement batches

Ver. 1.0 Session 11 Slide 1 of 31

Creating Views

A View is:
Used to view data from tables
Similar to creating tables but it does not contain any data as it
derives its data from the underlying tables
Created by using CREATE VIEW statement
Syntax:
CREATE VIEW view_name
[(column_name [, column_name]...)]
[WITH ENCRYPTION] [, SCHEMABINDING]]
AS select_statement [WITH CHECK OPTION]
Let’s see how…


Indexing Views

Indexing of Views:
Is done when the volume of data in the underlying table is
large and not updated frequently
Improves query performance
Is performed by creating an unique clustered index on a view
and afterwards nonclustered index can also be created
Is performed by using CREATE INDEX statement
Let’s see how…


Just a minute

In which of the following conditions will you NOT create an
indexed view:
1. When the data is large
2. When the data is regularly updated
3. When you need to improve the performance of the view

Answer:
2. When the data is regularly updated


Managing Views

Managing a view involves altering, dropping, or renaming.
Altering a view involves modifying a view without dropping
it.
Syntax:
ALTER VIEW view_name [(column_name)]
WITH ENCRYPTION]
AS select_statement
WITH CHECK OPTION]
Dropping a view involves deleting the view when it is no
longer required.
Syntax:
DROP VIEW view_name


Managing Views (Contd.)

Renaming the name of the view without deleting it.
Syntax:
sp_rename old_viewname, new_viewname
Let’s see how…


Demo: Creating Views

Problem Statement:
You are a database developer at AdventureWorks, Inc. You
need to frequently generate a report containing the following
details of the employees:
Employee ID
Employee First Name
Employee Last Name
Title
Manager First Name
Manager Last Name


Demo: Creating Views (Contd.)

Problem Statement (Contd.):
To retrieve this data, you need to execute the following
statement on the database:
SELECT e1.EmployeeID, c1.FirstName,
c1.LastName, e1.Title,
c2.FirstName AS [Manager First
Name],c2.LastName AS [Manager Last Name]
FROM HumanResources.Employee e1 INNER
JOIN Person.Contact c1
ON e1.ContactID = c1.ContactID INNER JOIN
HumanResources.Employee AS e2
ON e1.ManagerID = e2.EmployeeID INNER
JOIN Person.Contact AS c2
ON e2.ContactID = c2.ContactID



Problem Statement (Contd.):
As a database developer, you need to simplify the execution of
this query so that you do not need to send such a large query
to the database engine every time the report is required.



Solution:
To solve the preceding problem, you need to perform the
following tasks:
1. Create a view.
2. Verify the simplification of the query execution.


Configuring Full-Text Search

Full-Text Search:
Allows you to perform complex search on the data
Allows you to search for synonyms or antonyms of a particular
word
Feature is disabled by default
To retrieve the required details by using full-text, you need
to perform the following tasks:
1. Enable the full-text search in the database.
2. Create a full-text catalog.
3. Create a unique index.
4. Create a full-text index.
5. Populate the full-text index.
Let’s see how…


Searching Data by Using a Full-Text Search

To search using full-text index, use the following full-text
predicates:
– FREETEXT: Searches for any variation of a word or a group of
words given in the search column.
– CONTAINS: Searches for a specific phrase, for the proximity
of words within a text or for the exact match.
Let’s see how…


Just a minute

List the types of full-text index population methods.

Answer:
The three types of full-text index population methods
are:
1. Full population
2. Change tracking based population
3. Incremental timestamp based population


Just a minute

Which predicate is used to search for a specific phrase or
for an exact match?

Answer:
CONTAINS


Demo: Implementing Full-Text Search

Problem Statement:
The users at AdventureWorks, Inc. need to frequently search
for employees, customers, or vendors based on the location.
The location details of all these entities are stored in the
Address table in the Person schema. The users want to search
for addresses with different combinations of the words
specified in the search criteria. For example, they need to
search for the locations that contain the words ‘Santa’ and
‘drive’ in the AddressLine1 column. Similarly, they might need
to search for the locations that contain the words ‘Santa’ and
‘Street’ in the AddressLine1 column.
How will you enable the users to perform such a data search?


Demo: Implementing Full-Text Search (Contd.)

Solution:
To solve the preceding problem, you need to perform the
following tasks:
1. Enable the Full-text search on the AdventureWorks database.
2. Create a default full-text catalog.
3. Create a full-text index.
4. Search the data by using the CONTAINS predicate.


Creating Batches

Batch:
Is created to send a group of SQL statements together to SQL
Server for execution
Compiles the statements as a single executable unit called an
execution plan
Uses GO command at the end to send the SQL statements to
the instance of SQL Server
Uses variables to store values. They are:
• Local variables
• Global variables
Uses PRINT statement to display user-defined messages and
values of variables
Let’s see how…


Just a minute

Which of the following statements can be used within a
batch?
1. CREATE FUNCTION
2. CREATE RULE
3. DECLARE

Answer:
3. DECLARE


Using Constructs

Allow batches to perform conditional execution of
statements with the following control-of-flow statements:
IF…ELSE statement
CASE statement
WHILE statement


Using Constructs (Contd.)

IF…ELSE statement:
Performs a particular action based on the result of the boolean
expression
Syntax:
IF boolean_expression {sql_statement |
statement_block} [ELSE boolean_expression
{sql_statement | statement_block}]
Let’s see how…



CASE statement:
Evaluates a list of conditions and returns one of the various
possible results
Syntax:
CASE
WHEN boolean_expression THEN expression
[[WHEN boolean_expression THEN expression]
[...]]
[ELSE expression]
END
Let’s see how…



WHILE statement:
Executes a batch repeatedly as long as the given condition
holds true
Uses BREAK and CONTINUE statements to break the loop or
to continue the loop
Syntax:
WHILE boolean_expression
{sql_statement | statement_block}
[BREAK]
{sql_statement | statement_block}
[CONTINUE]
Let’s see how…


Handling Errors and Exceptions

Errors in SQL Server can be handled on two levels:
Using the TRY-CATCH construct
Using the RAISERROR statement


Handling Errors and Exceptions (Contd.)

TRY-CATCH construct is used in the following way:
Try block encloses a group of T-SQL statements. If any error
occurs in the statements of TRY block, control passes to the
CATCH block.
CATCH block encloses another group of statements, which
gets executed when an error occurs.
Let’s see how…


Handling Errors and Exceptions (Contd.)

RAISERROR:
Is used to return messages back to the called applications
Uses the same message format as a system error or warning
message generated by the SQL Server Database Engine
Can also return user-defined error messages
Let’s see how…


Just a minute

Which system function returns the text of the error message
when used in the CATCH block?

Answer:
ERROR_MESSAGE()


Just a minute

How can you return a user-defined error message in a
batch?

Answer:
Using the RAISERROR statement


Summary

In this session, you learned that:
A view is a virtual table, which derives its data from one or
more tables known as the base or underlying tables.
Views serve as security mechanisms, thereby protecting data
in the base tables.
The SQL Server allows data to be modified only in one of the
underlying tables when using views, even if the view is derived
from multiple underlying tables.
The SQL Server enables users to search for a wide range of
text in the SQL tables through a full-text query feature.
You can enable the full-text search by using the command,
SP_FULLTEXT_DATABASE ENABLE.
A full-text catalog can be created by using the CREATE
FULLTEXT CATALOG statement.


Summary (Contd.)

– A full-text index can be created by using the CREATE
FULLTEXT INDEX statement.
– Three types of full-text population methods are full population,
change tracking-based population, and incremental
timestamp-based population.
– Full-text predicates that can be used to perform full-text search
are CONTAINS and FREETEXT.
– A FREETEXT predicate searches for any variation of a word or
a group of words given in the search column.
– The CONTAINS predicate searches for a specific phrase or for
the exact match.
– A batch is a set of SQL statements submitted together to the
server for execution.
– You can use a variable to store a temporary value.


Summary (Contd.)

You can use the PRINT statement to display a user-defined
message or the content of a variable on the screen.
You can use the comment entries in batches to write a
description of the code.
You can use the IF…ELSE statement for conditional execution
of the SQL statements.
The CASE statement evaluates a list of conditions and returns
one of the various possible results.
You can use the WHILE statement in a batch to allow a set of
T-SQL statements to execute repeatedly as long as the given
condition holds true.
The BREAK statement causes an exit from the WHILE loop.


Summary (Contd.)

The CONTINUE statement causes the WHILE loop to restart,
skipping any statements after the CONTINUE statement within
the loop.
Two ways to handle errors in batches are:
• TRY-CATCH construct
• RAISERROR statement


08 qmds2005 session11

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