advanced features of oracle sql

8/14/2019 Advanced Features of Oracle SQL

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DCopyright 2004, Oracle. All rights reserved.

Advanced Features of Oracle SQL


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D-2 Copyright 2004, Oracle. All rights reserved.

Objectives

After completing this appendix, you should be able to:

Explain and create LOBs

Explain the need and benefits of PL/SQL

Identify the different types of PL/SQL blocks Use regular expression support in SQL to search,

match, and replace strings all in terms of regular

expressions

Employ proactive tuning methodologies


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Understanding Large Object Types

Types:

CLOB: Character

NCLOB: Multibyte character

BLOB: Binary BFILE: Binary file


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Differentiating Between LOB, LONG, andLONG RAWTypes

LONG and LONG RAW data canonly be accessed sequentially

LOBs can be accessed inrandom order

A table can have only one LONGorLONG RAW column

A table can contain multiple LOBcolumns

Stores up to 2 GB of dataStores up to 128 TB of data

LONG and LONG RAWLOB


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Using BFILES

Creating a table having a BFILE column:

Creating a directory object:

Inserting values into a BFILE:

CREATE TABLE department(dep_id INTEGER,dep_details BFILE);

CREATE OR REPLACE DIRECTORY file_locationAS C:\dept\files;

INSERT INTO department(dep_id,dep_details)VALUES(10,BFILENAME(file_location,details.doc));


7/48D-7 Copyright 2004, Oracle. All rights reserved.

What Is PL/SQL?

PL/SQL:

Stands for Procedural Language extension to SQL

Is Oracle Corporations standard data access

language for relational databases Seamlessly integrates procedural constructs with

SQL


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PL/SQL Environment

PL/SQL engine

Oracle database server

SQL statement

executor

Procedural

statement

executor

procedural

SQL

PL/SQL

block



Benefits of PL/SQL

SQLIF...THEN

SQLELSE

SQLEND IF;

SQL

Integration of procedural constructs with SQL

Improved performance

SQL 1

SQL 2



Benefits of PL/SQL

Modularized program development

Integration with Oracle tools

Portability

Exception handling



Benefits of PL/SQL



PL/SQL Block Structure

DECLARE (Optional)

Variables, cursors, user-defined exceptions

BEGIN (Mandatory)

- SQL statements- PL/SQL statements

EXCEPTION (Optional)

Actions to perform

when errors occurEND; (Mandatory)



PL/SQL Block Structure



Block Types

Anonymous Procedure

Function[DECLARE]

BEGIN--statements

[EXCEPTION]

END;

PROCEDURE nameIS

BEGIN--statements

[EXCEPTION]

END;

FUNCTION nameRETURN datatypeISBEGIN--statementsRETURN value;

[EXCEPTION]

END;



Block Types



Program Constructs

Application triggers

Application packages

Application proceduresor functions

Anonymous blocks

Tools Constructs

Object types

Database triggers

Stored packages

Stored procedures orfunctions

Anonymous blocks

Database Server

Constructs

Object types



Program Constructs



Creating an Anonymous Block

Enter the anonymous block in the iSQL*Plus

workspace:



Executing an Anonymous Block

Click the Execute button to execute the anonymous

block:

PL\SQL procedure successfully completed.



Test the Output of a PL/SQL Block

Enable output in iSQL*Plus with the commandSET SERVEROUTPUT ON.

Use a predefined Oracle package and itsprocedure:

DBMS_OUTPUT.PUT_LINE

SET SERVEROUTPUT ONDBMS_OUTPUT.PUT_LINE(' The First Name of the

Employee is ' || f_name);



Test the Output of a PL/SQL Block



Regular Expression Overview

ABC

A method ofdescribing bothsimple and complex

patterns forsearching andmanipulating

Several new

functions to

support regular

expressions

A multilingual

regular expressionsupport for SQL

and PLSQL string

types



Meta Characters

Specifies equivalence classes[==]

Matches one or more occurrence+

Matches zero or one occurrence?

Matches any character in the supported character set, except NULL.Grouping expression, treated as a single subexpression()

Back-reference expression\n

Specifies a character class and matches any character in that class[: :]

Can have four different meanings: 1. Stand for itself. 2. Quote the nextcharacter. 3. Introduce an operator. 4. Do nothing.

\

DescriptionSymbol

Specifies one collation element, such as a multicharacter element

Matches at least m times but no more than n times

Matches exactly m times

Bracket expression for a matching list matching any one of theexpressions represented in the list

Matches the start-of-line/end-of-line

Alteration operator for specifying alternative matches

Matches zero or more occurrences

[..]

{m,n}

{m}

[ ]

^/$

|

*



Using Meta CharactersProblem: Find 'abc' within a string:Solution: 'abc' Matches: abcDoes not match: 'def'

Problem: To find 'a' followed by any character, followedby 'c'

Meta Character: any character is defined by '.'Solution: 'a.c'

Matches: abc Matches: adc Matches: alc Matches: a&cDoes not match: abb

Problem: To find one or more occurrences of 'a'

Meta Character: Use'+' sign to match one or more of theprevious charactersSolution: 'a+' Matches: a Matches: aaDoes not match: bbb

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Notes Only


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Regular Expression Functions

Searches for a given string for a regularexpression pattern and returns the positionwhere the match is found

REGEXP_INSTR

Searches for a regular expression patternwithin a given string and returns the matchedsubstring

REGEXP_SUBSTR

Searches for a regular expression patternand replaces it with a replacement string

REGEXP_REPLACE

Similar to the LIKE operator, but performsregular expression matching instead ofsimple pattern matching

REGEXP_LIKE

DescriptionFunction Name


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The REGEXP Function Syntax

REGEXP_LIKE (srcstr, pattern [,match_option])

REGEXP_INSTR (srcstr, pattern [, position [, occurrence

[, return_option [, match_option]]]])

REGEXP_SUBSTR (srcstr, pattern [, position[, occurrence [, match_option]]])

REGEXP_REPLACE(srcstr, pattern [,replacestr [, position[, occurrence [, match_option]]]])


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SELECT street_address,REGEXP_INSTR(street_address,'[^[:alpha:]]')

FROM locationsWHERE

REGEXP_INSTR(street_address,'[^[:alpha:]]')> 1;

Checking the Presence of a Pattern


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SELECT REGEXP_SUBSTR(street_address , ' [^ ]+ ')"Road" FROM locations;

Example of Extracting Substrings


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SELECT REGEXP_REPLACE( country_name, '(.)','\1 ') "REGEXP_REPLACE"

FROM countries;

Replacing Patterns


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Regular Expressions and

Check Constraints

ALTER TABLE emp8ADD CONSTRAINT email_addrCHECK(REGEXP_LIKE(email,'@'))NOVALIDATE ;

INSERT INTO emp8 VALUES(500,'Christian','Patel','ChrisP2creme.com', 1234567890,'12-Jan-2004', 'HR_REP', 2000, null, 102, 40) ;

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Proactive Tuning Methodology

Simplifying design

Modeling data

Optimizing table and index design

Using views Writing efficient SQL

Sharing cursors

Using bind variables

Using dynamic SQL


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Simplifying Application Design

Simple tables

Well-written SQL

Indexing only as required

Retrieving optimum information


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Modeling Data

Accurately represent business practices

Focus on most frequent and important businesstransactions

Use modeling tools Normalize the data


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Optimizing Table Design

Compromise between flexibility and performance

Principally normalize

Selectively denormalize

Use Oracle performance features Default values

Check constraints

Materialized views

Clusters

Focus on business-critical tables


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Optimizing Index Design

Index keys

Primary key

Unique key

Foreign keys

Index often-queried data

Use SQL as a guide to index design.


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Using Views

Simplifies application design

Is transparent to the end user

Can cause suboptimal execution plans


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Increasing the Efficiency of SQL Execution

Good database connectivity

Using cursors

Minimizing parsing

Using bind variables


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Bind Variable Peeking

During the first invocation of a cursor, the queryoptimizer peeks at user-defined bind variable

values.

During subsequent invocations, no peeking takesplace, and the cursor is shared.


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Writing SQL to Share Cursors

Create generic code using the following:

Stored procedures and packages

Database triggers

Any other library routines and procedures Writing to format standards

Case

White space

Comments

Object references

Bind variables


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Dynamic SQL

Provides the ability to dynamically execute SQLstatements whose complete text is unknown until

execution time

Can place dynamic SQL statements directly into

PL/SQL blocks Consists of:

DML statements Queries PL/SQL anonymous blocks

DDL statements Transaction control statements Session control statements

Should be used cautiously


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Implementing the Application

Use an appropriate development environment.

Isolate software components.

Check that the application is complete and self

sufficient. Use programming languages for procedural logic.

Cache frequently accessed relatively constantdata.

Ensure seamless integration of applicationcomponents and scalability.

Enforce referential integrity using foreign keys.


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Summary

In this appendix, you should have learned how to:

Explain and create LOBs

Explain the need and benefits of PL/SQL

Identify the different types of PL/SQL blocks Use regular expression support in SQL to search,

match, and replace strings all in terms of regular

expressions

Employ proactive tuning methodologies

advanced features of oracle sql

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