This document discusses composite data types in PL/SQL including records, collections like index by tables and nested tables, and using explicit cursors. It provides examples of declaring different composite data types like records and index by tables, using %ROWTYPE attribute, and controlling explicit cursors through open, fetch, close operations and cursor attributes. It also discusses using cursors with parameters and FOR UPDATE/WHERE CURRENT OF clauses for locking and updating rows.
Cursores en Oracle PL/SQL, en esta presentación se encuentra información sobre que son, cuando se debe usar, su creación, invocación y también su eliminación.
PL/SQL is a combination of SQL along with the procedural features of programming languages.
It provides specific syntax for this purpose and supports exactly the same datatypes as SQL.
Displaying Data from Multiple Tables - Oracle Data BaseSalman Memon
After completing this lesson, you should be able to
do the following:
Write SELECT statements to access data from more than one table using equality and nonequality joins
View data that generally does not meet a join condition by using outer joins
Join a table to itself by using a self join
http://phpexecutor.com
This presentation deals with the fundamentals of SQL, Installation and Database concepts. Presented by our team in Alphalogic Inc: https://www.alphalogicinc.com/
After completing this lesson, you should be able to
do the following:
Describe the types of problem that subqueries can solve
Define subqueries
List the types of subqueries
Write single-row and multiple-row subqueries
http://phpexecutor.com
After completing this lesson, you should be able to
do the following:
List the capabilities of SQL SELECT statements
Execute a basic SELECT statement
Differentiate between SQL statements and iSQL*Plus commands
http://phpexecutor.com
What is PL/SQL
Procedural Language – SQL
An extension to SQL with design features of programming languages (procedural and object oriented)
PL/SQL and Java are both supported as internal host languages within Oracle products.
pl/sql online Training|sql online Training | iTeknowledgeMasood Khan
This Course is designed by iTeknowledge.com experts to provide concrete and indepth knowledge of sql and pl/sql.100%practical and instructor led live training.
Cursores en Oracle PL/SQL, en esta presentación se encuentra información sobre que son, cuando se debe usar, su creación, invocación y también su eliminación.
PL/SQL is a combination of SQL along with the procedural features of programming languages.
It provides specific syntax for this purpose and supports exactly the same datatypes as SQL.
Displaying Data from Multiple Tables - Oracle Data BaseSalman Memon
After completing this lesson, you should be able to
do the following:
Write SELECT statements to access data from more than one table using equality and nonequality joins
View data that generally does not meet a join condition by using outer joins
Join a table to itself by using a self join
http://phpexecutor.com
This presentation deals with the fundamentals of SQL, Installation and Database concepts. Presented by our team in Alphalogic Inc: https://www.alphalogicinc.com/
After completing this lesson, you should be able to
do the following:
Describe the types of problem that subqueries can solve
Define subqueries
List the types of subqueries
Write single-row and multiple-row subqueries
http://phpexecutor.com
After completing this lesson, you should be able to
do the following:
List the capabilities of SQL SELECT statements
Execute a basic SELECT statement
Differentiate between SQL statements and iSQL*Plus commands
http://phpexecutor.com
What is PL/SQL
Procedural Language – SQL
An extension to SQL with design features of programming languages (procedural and object oriented)
PL/SQL and Java are both supported as internal host languages within Oracle products.
pl/sql online Training|sql online Training | iTeknowledgeMasood Khan
This Course is designed by iTeknowledge.com experts to provide concrete and indepth knowledge of sql and pl/sql.100%practical and instructor led live training.
Case study what you can take to the bank(primary functions)rehaniltifat
Case study - what you can take to the bank(Primary functions of a bank), demonstrated at Sheikh Zayed Islamic Centre, University of Karachi in PGD (Second Semester) program for the subject Case Studies for Islamic Banking Institutions. A presentation on "Organizational Structures in Islamic Banking Institutions and functions of a bank and their Job Descriptions" assigned by Mr. Abdul Jabbar Karimi from HMB Bank Limited.
Transcript of Presentation(Simple & Compound Interest) for Audiencerehaniltifat
Transcript for Simple & Compound Interest presentation demonstrated at Sheikh Zayed Islamic Centre, University of Karachi. PGD in Islamic Banking & Finance. Course Supervisor: Dr. Zaki ur Rahman (Chairman - Karachi University Business School) Subject: Introduction to Islamic Business & Finance Produced by: Rehan Ahmed (Oct, 2011)
Turbocharge SQL Performance in PL/SQL with Bulk ProcessingSteven Feuerstein
Is your Oracle Database application running slower than you'd like? One of the first things to check is row-by-row processing: non-query DML (insert, update, delete) within a loop. And the fix? Bulk processing, either with smarter SQL or with FORALL and BULK COLLECT in PL/SQL.
After completing this lesson, you should be able to do the following:
Create user-defined PL/SQL records
Create a record with the %ROWTYPE attribute
Create a PL/SQL table
Create a PL/SQL table of records
Describe the difference between records, tables, and tables of records
Creating and Managing Tables -Oracle Data base Salman Memon
After completing this lesson, you should be able to
do the following:
Describe the main database objects
Create tables
Describe the data types that can be used when specifying column definition
Alter table definitions
Drop, rename, and truncate tables
http://phpexecutor.com
DDL. data defination language for creating databaseSHAKIR325211
data defination language database management systems how to create a databse how to insert a record and how to select a particular coloums and fields for instance select records from employee database or select fields of particular coloumns in database than wright query Similarly, the meaning of a query in database management is a request for data . If you need to access, manipulate, delete, or retrieve data from your relational database, you'll need a database query written using a specific syntax. Our SQL tutorial will teach you how to use SQL in: MySQL, SQL Server, MS Access, Oracle, Sybase, Informix, Postgres, and other database systems.If you are adding values for all the columns of the table, you do not need to specify the column names in the SQL query. However, make sure the order of the values is in the same order as the columns in the table. Here, the INSERT INTO syntax would be as follows and somany features in database management systms Data is a collection of a distinct small unit of information. It can be used in a variety of forms like text, numbers, media, bytes, etc. it can be stored in pieces of paper or electronic memory, etc.
Word 'Data' is originated from the word 'datum' that means 'single piece of information.' It is plural of the word datum.
In computing, Data is information that can be translated into a form for efficient movement and processing. Data is interchangeable. You can organize data into tables, rows, columns, and index it to make it easier to find relevant information.
Database handlers create a database in such a way that only one set of software program provides access of data to all the users.
The main purpose of the database is to operate a large amount of information by storing, retrieving, and managing data.
There are many dynamic websites on the World Wide Web nowadays which are handled through databases. For example, a model that checks the availability of rooms in a hotel. It is an example of a dynamic website that uses a database.
There are many databases available like MySQL, Sybase, Oracle, MongoDB, Informix, PostgreSQL, SQL Server, etc.
Modern databases are managed by the database management system (DBMS). 1968 was the year when File-Based database were introduced. In file-based databases, data was maintained in a flat file. Though files have many advantages, there are several limitations.
One of the major advantages is that the file system has various access methods, e.g., sequential, indexed, and random.
It requires extensive programming in a third-generation language such as COBOL, BASIC.Cloud database facilitates you to store, manage, and retrieve their structured, unstructured data via a cloud platform. This data is accessible over the Internet. Cloud databases are also called a database as service (DBaaS) because they are offered as a managed service.A NoSQL database is an approach to design such databases that can accommodate a wide variety of data models. NoSQL can handle an exte
Structured Query Language
SQL Commands:
• The standard SQL commands to interact with relational databases are CREATE, SELECT, INSERT, UPDATE, DELETE and DROP
SQL: Structured Query Language
Includes:
Introduction
It is a computer programming language that is used for storage, retrieval and manipulation of data that is stored in relational database. This is a standard computer programming language used for RDMS (Relational Database Management Systems).
IBM’s Ted Cod a.k.a Father of Relational databases gave the concept of relational model for database in 1970. It was 4 years later SQL appeared in 1974. This was just an idea, which got conceptualized in the form of Systems/R in 1978 and was released by IBM. The ANSI standards and first prototype of relational databases was released in 1986, which is popularly knows as Oracle
Advantages:
Used for accessing data in RDBMS.
Used for describing data.
Definition of data and its manipulation.
Can be used with other programming language by embedding SQL modules into other languages code, pre-compilers and libraries.
Possible to create and drop data base using this programming language.
Setting permission on views, table and procedures.
Can be used for creating views, procedures and functions.
Commands
Commands in SQL are categorized into three category namely
DDL – Data definition language
DML – Data Manipulation language
DCL – Data Control language
Data Definition Language (DDL)
Commands that are classified under DDL category are as follows:
CREATE – Used for creating an object, table/view.
ALTER – Used for modifying an existing database object.
DROP – Object, table an views created using CREATE can be deleted/removed.
Data Manipulation Language (DML)
Commands that are classified under DML are as follows:
SELECT – Used for retrieving a set of records from one/more than one tables.
DELETE – Used for deleting records.
UPDATE – Used for modifying / updating records.
INSERT – Used for inserting records.
Data Control Language (DCL)
Commands that have been classified under DCL are:
GRANT – Users can be granted permission / privileges using this command
REVOKE – Privileges to the user can be taken back using this command.
Constraints
Rules are enforced on the columns of the table that contain data specific for the field for all the record in the table. These rules are referred to as constraints, which are generally used to ensure that field only gets a particular type of value. For instance if there is a field called “Age” in the table, then this field can only take numeric value.
Constraints set up for the table apply to all the data stored in the table.
Some of the common constraints are:
NOT NULL:
This constraints ensure that the field value is never set to NULL
DEFAULT:
Typically used to fill in a default value for any field left blank.
UNIQUE:
If the constraints is set on a column, then all value set for this field will have to be unique
Consists of the explanations of the basics of SQL and commands of SQL.Helpful for II PU NCERT students and also degree studeents to understand some basic things.
After completing this lesson, you should be able to do the following:
Describe some database objects and their uses
Create, maintain, and use sequences
Create and maintain indexes
Create private and public synonyms
PHP Frameworks: I want to break free (IPC Berlin 2024)Ralf Eggert
In this presentation, we examine the challenges and limitations of relying too heavily on PHP frameworks in web development. We discuss the history of PHP and its frameworks to understand how this dependence has evolved. The focus will be on providing concrete tips and strategies to reduce reliance on these frameworks, based on real-world examples and practical considerations. The goal is to equip developers with the skills and knowledge to create more flexible and future-proof web applications. We'll explore the importance of maintaining autonomy in a rapidly changing tech landscape and how to make informed decisions in PHP development.
This talk is aimed at encouraging a more independent approach to using PHP frameworks, moving towards a more flexible and future-proof approach to PHP development.
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
Essentials of Automations: Optimizing FME Workflows with ParametersSafe Software
Are you looking to streamline your workflows and boost your projects’ efficiency? Do you find yourself searching for ways to add flexibility and control over your FME workflows? If so, you’re in the right place.
Join us for an insightful dive into the world of FME parameters, a critical element in optimizing workflow efficiency. This webinar marks the beginning of our three-part “Essentials of Automation” series. This first webinar is designed to equip you with the knowledge and skills to utilize parameters effectively: enhancing the flexibility, maintainability, and user control of your FME projects.
Here’s what you’ll gain:
- Essentials of FME Parameters: Understand the pivotal role of parameters, including Reader/Writer, Transformer, User, and FME Flow categories. Discover how they are the key to unlocking automation and optimization within your workflows.
- Practical Applications in FME Form: Delve into key user parameter types including choice, connections, and file URLs. Allow users to control how a workflow runs, making your workflows more reusable. Learn to import values and deliver the best user experience for your workflows while enhancing accuracy.
- Optimization Strategies in FME Flow: Explore the creation and strategic deployment of parameters in FME Flow, including the use of deployment and geometry parameters, to maximize workflow efficiency.
- Pro Tips for Success: Gain insights on parameterizing connections and leveraging new features like Conditional Visibility for clarity and simplicity.
We’ll wrap up with a glimpse into future webinars, followed by a Q&A session to address your specific questions surrounding this topic.
Don’t miss this opportunity to elevate your FME expertise and drive your projects to new heights of efficiency.
UiPath Test Automation using UiPath Test Suite series, part 3DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 3. In this session, we will cover desktop automation along with UI automation.
Topics covered:
UI automation Introduction,
UI automation Sample
Desktop automation flow
Pradeep Chinnala, Senior Consultant Automation Developer @WonderBotz and UiPath MVP
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Builder.ai Founder Sachin Dev Duggal's Strategic Approach to Create an Innova...Ramesh Iyer
In today's fast-changing business world, Companies that adapt and embrace new ideas often need help to keep up with the competition. However, fostering a culture of innovation takes much work. It takes vision, leadership and willingness to take risks in the right proportion. Sachin Dev Duggal, co-founder of Builder.ai, has perfected the art of this balance, creating a company culture where creativity and growth are nurtured at each stage.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
"Impact of front-end architecture on development cost", Viktor TurskyiFwdays
I have heard many times that architecture is not important for the front-end. Also, many times I have seen how developers implement features on the front-end just following the standard rules for a framework and think that this is enough to successfully launch the project, and then the project fails. How to prevent this and what approach to choose? I have launched dozens of complex projects and during the talk we will analyze which approaches have worked for me and which have not.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
LF Energy Webinar: Electrical Grid Modelling and Simulation Through PowSyBl -...DanBrown980551
Do you want to learn how to model and simulate an electrical network from scratch in under an hour?
Then welcome to this PowSyBl workshop, hosted by Rte, the French Transmission System Operator (TSO)!
During the webinar, you will discover the PowSyBl ecosystem as well as handle and study an electrical network through an interactive Python notebook.
PowSyBl is an open source project hosted by LF Energy, which offers a comprehensive set of features for electrical grid modelling and simulation. Among other advanced features, PowSyBl provides:
- A fully editable and extendable library for grid component modelling;
- Visualization tools to display your network;
- Grid simulation tools, such as power flows, security analyses (with or without remedial actions) and sensitivity analyses;
The framework is mostly written in Java, with a Python binding so that Python developers can access PowSyBl functionalities as well.
What you will learn during the webinar:
- For beginners: discover PowSyBl's functionalities through a quick general presentation and the notebook, without needing any expert coding skills;
- For advanced developers: master the skills to efficiently apply PowSyBl functionalities to your real-world scenarios.
Composite Data Types You have learned that variables of scalar data type can hold only one value, whereas a variable of composite data type can hold multiple values of scalar data type or composite data type. There are two types of composite data types: PL/SQL records: Records are used to treat related but dissimilar data as a logical unit. A PL/SQL record can have variables of different types. For example, you can define a record to hold employee details. This involves storing an employee number as NUMBER , a first name and last name as VARCHAR2 , and so on. By creating a record to store employee details, you create a logical collective unit. This makes data access and manipulation easier. PL/SQL collections: Collections are used to treat data as a single unit. Collections are of three types: INDEX BY tables or associative arrays Nested table VARRAY Why Use Composite Data Types? You have all the related data as a single unit. You can easily access and modify the data. Data is easier to manage, relate, and transport if it is composite. An analogy is having a single bag for all your laptop components rather than a separate bag for each component.
Composite Data Types (continued) If both PL/SQL records and PL/SQL collections are composite types, how do you choose which one to use? Use PL/SQL records when you want to store values of different data types that are logically related. If you create a record to hold employee details, indicate that all the values stored are related because they provide information about a particular employee. Use PL/SQL collections when you want to store values of the same data type. Note that this data type can also be of the composite type (such as records). You can define a collection to hold the first names of all employees. You may have stored n names in the collection; however, name 1 is not related to name 2. The relation between these names is only that they are employee names. These collections are similar to arrays in programming languages such as C, C++, and Java.
PL/SQL Records A record is a group of related data items stored in fields , each with its own name and data type. Each record defined can have as many fields as necessary. Records can be assigned initial values and can be defined as NOT NULL . Fields without initial values are initialized to NULL . The DEFAULT keyword can also be used when defining fields. You can define RECORD types and declare user-defined records in the declarative part of any block, subprogram, or package. You can declare and reference nested records. One record can be the component of another record.
Creating a PL/SQL Record PL/SQL records are user-defined composite types. To use them: 1. Define the record in the declarative section of a PL/SQL block. The syntax for defining the record is shown in the slide. 2. Declare (and optionally initialize) the internal components of this record type. In the syntax: type_name Is the name of the RECORD type (This identifier is used to declare records.) field_name Is the name of a field within the record field_type Is the data type of the field (It represents any PL/SQL data type except REF CURSOR . You can use the %TYPE and %ROWTYPE attributes.) expr Is the field_type or an initial value The NOT NULL constraint prevents assigning nulls to those fields. Be sure to initialize the NOT NULL fields. REF CURSOR is covered in appendix C (“ REF Cursors”).
PL/SQL Record Structure Fields in a record are accessed with the name of the record. To reference or initialize an individual field, use the dot notation: record_name.field_name For example, you reference the job_id field in the emp_record record as follows: emp_record.job_id You can then assign a value to the record field: emp_record.job_id := 'ST_CLERK'; In a block or subprogram, user-defined records are instantiated when you enter the block or subprogram. They cease to exist when you exit the block or subprogram.
%ROWTYPE Attribute You have learned that %TYPE is used to declare a variable of a column type. The variable has the same data type and size as the table column. The benefit of %TYPE is that you do not have to change the variable if the column is altered. Also, if the variable is used in any calculations, you need not worry about its precision. The %ROWTYPE attribute is used to declare a record that can hold an entire row of a table or view. The fields in the record take their names and data types from the columns of the table or view. The record can also store an entire row of data fetched from a cursor or cursor variable. The slide shows the syntax for declaring a record. In the syntax: In the following example, a record is declared using %ROWTYPE as a data type specifier: DECLARE emp_record employees%ROWTYPE; ... identifier Is the name chosen for the record as a whole reference Is the name of the table, view, cursor, or cursor variable on which the record is to be based (The table or view must exist for this reference to be valid.)
%ROWTYPE Attribute (continued) The emp_record record has a structure consisting of the following fields, each representing a column in the employees table. Note: This is not code but simply the structure of the composite variable. (employee_id NUMBER(6), first_name VARCHAR2(20), last_name VARCHAR2(20), email VARCHAR2(20), phone_number VARCHAR2(20), hire_date DATE, salary NUMBER(8,2), commission_pct NUMBER(2,2), manager_id NUMBER(6), department_id NUMBER(4)) To reference an individual field, use dot notation: record_name.field_name For example, you reference the commission_pct field in the emp_record record as follows: emp_record.commission_pct You can then assign a value to the record field: emp_record.commission_pct:= .35; Assigning Values to Records You can assign a list of common values to a record by using the SELECT or FETCH statement. Make sure that the column names appear in the same order as the fields in your record. You can also assign one record to another if both have the same corresponding data types. A user-defined record and a %ROWTYPE record never have the same data type.
Advantages of Using %ROWTYPE The advantages of using the %ROWTYPE attribute are listed in the slide. Use the %ROWTYPE attribute when you are not sure about the structure of the underlying database table. The main advantage of using %ROWTYPE is that it simplifies maintenance. Using %ROWTYPE ensures that the data types of the variables declared with this attribute change dynamically when the underlying table is altered. If a DDL statement changes the columns in a table, then the PL/SQL program unit is invalidated. When the program is recompiled, it will automatically reflect the new table format. The %ROWTYPE attribute is particularly useful when you want to retrieve an entire row from a table. In the absence of this attribute, you would be forced to declare a variable for each of the columns retrieved by the select statement.
INDEX BY Tables or Associative Arrays INDEX BY tables are composite types (collections) and are user defined. INDEX BY tables can store data using a primary key value as the index, where the key values are not sequential. INDEX BY tables are sets of key-value pairs. (You can imagine data stored in two columns, although the key and value pairs are not exactly stored in columns.) INDEX BY tables have only two columns: A column of integer or string type that acts as the primary key. The key can be numeric, either BINARY_INTEGER or PLS_INTEGER . The BINARY_INTEGER and PLS_INTEGER keys require less storage than NUMBER . They are used to represent mathematical integers compactly and to implement arithmetic operations by using machine arithmetic. Arithmetic operations on these data types are faster than NUMBER arithmetic. The key can also be of type VARCHAR2 or one of its subtypes. The examples in this course use the PLS_INTEGER data type for the key column. A column of scalar or record data type to hold values. If the column is of scalar type, it can hold only one value. If the column is of record type, it can hold multiple values. The INDEX BY tables are unconstrained in size. However, the key in the PLS_INTEGER column is restricted to the maximum value that a PLS_INTEGER can hold. Note that the keys can be both positive and negative. The keys in INDEX BY tables are not in sequence.
Creating an INDEX BY Table There are two steps involved in creating an INDEX BY table. 1. Declare a TABLE data type. 2. Declare a variable of that data type. In the syntax:
INDEX BY Table Structure Like the size of a database table, the size of an INDEX BY table is unconstrained. That is, the number of rows in an INDEX BY table can increase dynamically so that your INDEX BY table grows as new rows are added. INDEX BY tables can have one column and a unique identifier to that column, neither of which can be named. The column can belong to any scalar or record data type, but the primary key must belong to the types PLS_INTEGER or BINARY_INTEGER . You cannot initialize an INDEX BY table in its declaration. An INDEX BY table is not populated at the time of declaration. It contains no keys or values. An explicit executable statement is required to populate the INDEX BY table.
Using INDEX BY Table Methods An INDEX BY table method is a built-in procedure or function that operates on a PL/SQL table and is called by using dot notation. Syntax: table_name.method_name [ ( parameters ) ]
INDEX BY Table of Records At any particular time, an INDEX BY table declared as a table of scalar data type can store the details of only one column in a database table. There is often a need to store all the columns retrieved by a query. The INDEX BY table of records offers a solution to this. Because only one table definition is needed to hold information about all the fields of a database table, the table of records greatly increases the functionality of INDEX BY tables. Referencing a Table of Records In the example in the slide, you can refer to fields in the dept_table record because each element of the table is a record. Syntax: table(index).field Example: dept_table(15).location_id := 1700; location_id represents a field in dept_table .
Nested Tables The functionality of nested tables is similar to that of INDEX BY tables; however, there are differences in the nested table implementation. The nested table is a valid data type in a schema-level table, but an INDEX BY table is not. The key type for nested tables is not PLS_INTEGER . The key cannot be a negative value (unlike in the INDEX BY table). Though we are referring to the first column as key, there is no key in a nested table. There is a column with numbers in sequence that is considered as the key column. Elements can be deleted from anywhere in a nested table, leaving a sparse table with nonsequential keys. The rows of a nested table are not in any particular order. When you retrieve values from a nested table, the rows are given consecutive subscripts starting from 1. Nested tables can be stored in the database (unlike INDEX BY tables). Syntax: TYPE type _ name IS TABLE OF {column _ type | variable%TYPE | table.column%TYPE} [NOT NULL] | table.%ROWTYPE In Oracle Database 10 g , nested tables can be compared for equality. You can check if an element exists in a nested table and also if a nested table is a subset of another.
VARRAY A variable-size array ( VARRAY) is similar to a PL/SQL table, except that a VARRAY is constrained in size. VARRAY is valid in a schema-level table. Items of VARRAY type are called VARRAY s. VARRAY s have a fixed upper bound. You have to specify the upper bound when you declare them. This is similar to arrays in the C language. The maximum size of a VARRAY is 2 GB, as in nested tables. The distinction between a nested table and a VARRAY is the physical storage mode. The elements of a VARRAY are stored contiguously in memory and not in the database. You can create a VARRAY type in the database by using SQL. Example: TYPE location_type IS VARRAY(3) OF locations.city%TYPE; offices location_type; The size of this VARRAY is restricted to 3. You can initialize a VARRAY by using constructors. If you try to initialize the VARRAY with more than three elements, a “Subscript outside of limit” error message is displayed.
Cursors The Oracle server uses work areas (called private SQL areas ) to execute SQL statements and to store processing information. You can use explicit cursors to name a private SQL area and to access its stored information. The Oracle server implicitly opens a cursor to process each SQL statement that is not associated with an explicitly declared cursor. Using PL/SQL, you can refer to the most recent implicit cursor as the SQL cursor.
Explicit Cursor Operations You declare explicit cursors in PL/SQL when you have a SELECT statement that returns multiple rows. You can process each row returned by the SELECT statement. The set of rows returned by a multiple-row query is called the active set . Its size is the number of rows that meet your search criteria. The diagram in the slide shows how an explicit cursor “points” to the current row in the active set . This enables your program to process the rows one at a time. Explicit cursor functions: Can do row-by-row processing beyond the first row returned by a query Keep track of which row is currently being processed Enable the programmer to manually control explicit cursors in the PL/SQL block
Controlling Explicit Cursors Now that you have a conceptual understanding of cursors, review the steps to use them. 1. In the declarative section of a PL/SQL block, declare the cursor by naming it and defining the structure of the query to be associated with it. 2. Open the cursor. The OPEN statement executes the query and binds any variables that are referenced. Rows identified by the query are called the active set and are now available for fetching. 3. Fetch data from the cursor. In the flow diagram shown in the slide, after each fetch you test the cursor for any existing row. If there are no more rows to process, you must close the cursor. 4. Close the cursor. The CLOSE statement releases the active set of rows. It is now possible to reopen the cursor to establish a fresh active set.
Controlling Explicit Cursors (continued) A PL/SQL program opens a cursor, processes rows returned by a query, and then closes the cursor. The cursor marks the current position in the active set. 1. The OPEN statement executes the query associated with the cursor, identifies the active set, and positions the cursor at the first row. 2. The FETCH statement retrieves the current row and advances the cursor to the next row until either there are no more rows or until a specified condition is met. 3. The CLOSE statement releases the cursor.
Cursor FOR Loops You have learned to fetch data from cursors by using simple loops. You now learn to use a cursor FOR loop, which processes rows in an explicit cursor. It is a shortcut because the cursor is opened, a row is fetched once for each iteration in the loop, the loop exits when the last row is processed, and the cursor is closed automatically. The loop itself is terminated automatically at the end of the iteration where the last row is fetched. In the syntax: record_name Is the name of the implicitly declared record cursor_name Is a PL/SQL identifier for the previously declared cursor Guidelines Do not declare the record that controls the loop; it is declared implicitly. Test the cursor attributes during the loop, if required. Supply the parameters for a cursor, if required, in parentheses following the cursor name in the FOR statement.
Explicit Cursor Attributes As with implicit cursors, there are four attributes for obtaining status information about a cursor. When appended to the cursor variable name, these attributes return useful information about the execution of a cursor manipulation statement. Note: You cannot reference cursor attributes directly in a SQL statement.
Cursors with Parameters You can pass parameters to a cursor in a cursor FOR loop. This means that you can open and close an explicit cursor several times in a block, returning a different active set on each occasion. For each execution, the previous cursor is closed and reopened with a new set of parameters. Each formal parameter in the cursor declaration must have a corresponding actual parameter in the OPEN statement. Parameter data types are the same as those for scalar variables, but you do not give them sizes. The parameter names are for references in the query expression of the cursor. In the syntax: The parameter notation does not offer greater functionality; it simply allows you to specify input values easily and clearly. This is particularly useful when the same cursor is referenced repeatedly. cursor_name Is a PL/SQL identifier for the declared cursor parameter_name Is the name of a parameter datatype Is the scalar data type of the parameter select_statement Is a SELECT statement without the INTO clause
FOR UPDATE Clause If there are multiple sessions for a single database, there is the possibility that the rows of a particular table were updated after you opened your cursor. You see the updated data only when you reopen the cursor. Therefore, it is better to have locks on the rows before you update or delete rows. You can lock the rows with the FOR UPDATE clause in the cursor query. In the syntax: The FOR UPDATE clause is the last clause in a select statement, even after ORDER BY (if it exists). When querying multiple tables, you can use the FOR UPDATE clause to confine row locking to particular tables. FOR UPDATE OF col_name(s) locks rows only in tables that contain col_name(s) . column_reference Is a column in the table against which the query is performed (A list of columns may also be used.) NOWAIT Returns an Oracle server error if the rows are locked by another session.
WHERE CURRENT OF Clause The WHERE CURRENT OF clause is used in conjunction with the FOR UPDATE clause to refer to the current row in an explicit cursor. The WHERE CURRENT OF clause is used in the UPDATE or DELETE statement, whereas the FOR UPDATE clause is specified in the cursor declaration. You can use the combination for updating and deleting the current row from the corresponding database table. This enables you to apply updates and deletes to the row currently being addressed, without the need to explicitly reference the row ID. You must include the FOR UPDATE clause in the cursor query so that the rows are locked on OPEN . In the syntax: cursor Is the name of a declared cursor (The cursor must have been declared with the FOR UPDATE clause.)
Practice 7: Overview In this practice, you apply your knowledge of cursors to process a number of rows from a table and populate another table with the results using a cursor FOR loop. You also write a cursor with parameters.