EDUCBA

EDUCBA

MENUMENU
  • Free Tutorials
  • Free Courses
  • Certification Courses
  • 360+ Courses All in One Bundle
  • Login

PL/SQL exists

Home » Data Science » Data Science Tutorials » Database Management Tutorial » PL/SQL exists

PL/SQL exists

Introduction to PL/SQL exists

PL/SQL exists is the statement in PL/ SQL which is used for checking whether any of the rows exist in the supplied parameters. This clause is most often used in the subqueries inside the where clause. If the subquery returns even a single row then the execution of the inner query stops there itself and the existing statement returns true. In case if till the last row of the table of the subquery is scanned for its execution still there is no row retrieved till the end then the exists function returns false.

In this article, we will study the syntax of the exist statement and will also look at the implementation of the existing function inside the subqueries of where clause with the help of examples. Further, we will also throw a little light on what is the difference between the exist function and the in a clause in PL/ SQL.

Start Your Free Data Science Course

Hadoop, Data Science, Statistics & others

Syntax:

The exists function is mostly used inside the where clause by specifying a subquery inside the parameter of the exists function for checking the existence of any row returned by the subquery. The syntax of the PL/ SQL exists function is as shown below –

SELECT *
FROM name of the table
WHERE EXISTS (subquery);

The terminologies that are used in the specified syntax are described one by one in the upcoming section –

  • Name of table – This is the table name from which we might want to retrieve the result of the final query provided if there is any existence of the row returned by the subquery.
  • Subquery – This is a select query statement that will involve retrieving some value from a particular table. This can also be a function call of a procedure call that returns the particular values. The returning result set of this subquery becomes the deciding factor about the Boolean value to be returned by the exist function.
  • EXISTS – This function checks if there is any value or row returned from the subquery and if at all while scanning the rows by the inner subquery even if a single row is returned, the exists function stops the further execution of the subquery and returns the TRUE Boolean value. If while retrieving the rows from the subquery, not even a single row is retrieved till the end then the EXISTS function returns the FALSE Boolean value.
  • Return value – The EXISTS function returns a Boolean value of there is existence of any row inside the subquery specified in the parameter.

Examples

Let us look at one example which will help us demonstrate the implementation and usage of the EXISTS function in PL/ SQL. We have two tables named employee_details and contact_details. The contents of each of the tables are as shown by the output of below two queries –

SELECT * FROM [contact_details];

The output of the execution of the above query is –

PL SQL exists 1

SELECT * FROM [employee_details];

The output of the execution of the above query is –

PL SQL exists 2

Now, we will try to retrieve only those employees who have their contact-related details present in the contact_details table. For this, we will make the use of EXIST function in PL/ SQL and our query statement will look somewhat like the below one –

SELECT
*
FROM
employee_details e
WHERE
EXISTS (
SELECT
1
FROM
contact_details
WHERE
employee_id = e.employee_id
);

Popular Course in this category
Sale
SQL Training Program (7 Courses, 8+ Projects)7 Online Courses | 8 Hands-on Projects | 73+ Hours | Verifiable Certificate of Completion | Lifetime Access
4.5 (8,882 ratings)
Course Price

View Course

Related Courses
PL SQL Training (4 Courses, 2+ Projects)Oracle Training (14 Courses, 8+ Projects)

PL SQL exists 3

EXISTS versus IN –

Basically, the functionality of both functions is quite similar. The EXISTS function checks if any row is returned by subquery while IN function scans all the values specified in its parameter for checking or comparing. The scanning of rows is stopped when the first row is found in the subquery of EXISTS function while in IN clause the scanning of rows continues till the end.
One more substantial difference between the usage of both the functions is that the EXISTS function can compare any value with NULL value while in the case of IN clause the NULL values are not compared with anything. In order to understand this, let us consider some examples.
We have one table with the name employee_details whose details are retrieved by using the following query statement –

SELECT * FROM [employee_details]

The output of execution of above query statement is as shown below –

PL SQL exists 4

Now, we will firstly make the use of EXISTS statement in the subquery as NULL and try to retrieve the records of the employee_details table. For this, we will be using the following query statement –

SELECT
*
FROM
employee_details
WHERE
EXISTS (
SELECT
NULL
FROM
dual
);

The output of execution of above query statement is as shown below returning all the rows of the employee details. This was because the EXISTS function compared all the rows with the NULL value.

result

Now, if we try to execute a similar kind of query to retrieve the rows of employee details by using the IN clause in the WHERE clause and passing it NULL values as shown in the below query statement, the output will not return any rows because the IN statement cannot compare the rows with NULL.

SELECT
*
FROM
employee_details
WHERE
employee_id IN(NULL);

The output of execution of above query statement is as shown below –

result 1

The execution of the EXISTS operator is fast as compared to IN clause when the result set of the subquery is substantially large. If the result set of the subquery results in a very small number of rows then the IN clause works faster than the EXISTS clause.

Conclusion

The PL/ SQL exists function is used for checking if any of the rows is returned by the subquery passed as a parameter to this function. This function is mostly used in the WHERE clause which acts as a deciding factor for performing the main query which can be select, insert, update or delete. The return value of the EXISTS function is a Boolean value which is true if even a single row is returned by subquery. Along with that the EXISTS function also stops the execution of the inner subquery if it even finds one row returned by it.

Recommended Articles

This is a guide to PL/SQL exists. Here we discuss Introduction, syntax, along with examples respectively. You may also have a look at the following articles to learn more –

  1. PL/SQL NVL
  2. PL/SQL Anonymous Block
  3. PL/SQL stored procedure
  4. PL/SQL GROUP BY

All in One Data Science Bundle (360+ Courses, 50+ projects)

360+ Online Courses

50+ projects

1500+ Hours

Verifiable Certificates

Lifetime Access

Learn More

0 Shares
Share
Tweet
Share
Primary Sidebar
Database Management Tutorial
  • PL/SQL
    • What is PL/SQL?
    • Careers in PL/SQL
    • PLSQL procedure
    • PL/SQL Exception
    • PL/SQL LIKE
    • PL/SQL Raise Exception
    • PLSQL rowtype
    • PLSQL? bind variables
    • PL/SQL Record
    • PL/SQL WITH
    • PL/SQL bulk collect
    • PL/SQL Block Structure
    • PL/SQL else if
    • PL/SQL nvl2
    • PL/SQL Package
    • PL/SQL exists
    • PL/SQL instr
    • PL/SQL listagg
    • PL/ SQL Formatter
    • PLSQLlength
    • PL/SQL Commands
    • PL/SQL Data Types
    • CASE statement in PL/SQL
    • PL/SQL IF Statement
    • Loops in PL/SQL
    • PL/SQL Add Column
    • For Loop in PLSQL
    • PL/SQL Cursor Loop
    • PLSQL Array
    • Cursors in PL/SQL
    • PL/SQL FOR Loop Cursor
    • PL/SQL Queries
    • PL/SQL SELECT INTO
    • PL/SQL TO_CHAR
    • PL/SQL UNION
    • PL/SQL NOT EQUAL
    • PL/SQL varray
    • PL/SQL Concatenate
    • PL/SQL UPDATE
    • PL/SQL TRIM
    • PL/SQL GROUP BY
    • PL/SQL GOTO
    • PL/SQL Date Functions
    • PL/ SQL having
    • PL/SQL to_DATE
    • PL/SQL NVL
    • PLSQL format date
    • PLSQL mod
    • PLSQL round
    • PL/SQL Boolean
    • PL/SQL exit
    • PL/SQL DECODE
    • PL/SQL ROWNUM
    • PLSQL?pivot
    • PLSQL string functions
    • PL/SQL Block
    • PL/SQL Function
    • PL/SQL Unwrapper
    • PL/SQL Table
    • PL/SQL ALTER TABLE
    • PLSQL execute immediate
    • Triggers in PL/SQL
    • PL/SQL Collections
    • PL/SQL stored procedure
    • PL/SQL Anonymous Block
    • PLSQL Interview Questions
  • DataBase Management
    • Text Data Mining
    • Roles of Database Management System in Industry
    • SQL Server Database Management Tools
    • Database administrator skills
    • Database Management Systems Advantages
    • Database Testing Interview Questions
    • Data Administrator
    • Database Administrator
    • Database Management Software
    • DataStage
    • Types of Database Models
    • Types of Database
    • Hierarchical Database Model
    • Relational Database
    • Relational Database Advantages
    • Operational Database
    • What is RDBMS?
    • What is DB2?
    • Data Masking Tools
    • Database Security
    • Data Replication
    • Bitmap Indexing
    • Second Normal Form
    • Third Normal Form
    • Fourth Normal Form
    • Data Definition Language
    • Data Manipulation Language
    • Data Control Language
    • Transaction Control Language
    • Conceptual Data Model
    • Entity-Relationship Model
    • Relational Database Model
    • Sequential File Organization
    • Checkpoint in DBMS
    • Teradata Create Table
    • Centralized Database
    • Data Storage in Database
    • Thomas write Rule
    • DBA Interview Questions
    • What is JDBC?
    • jdbc hive
    • Apriori Algorithm
    • JDBC Architecture
    • JDBC Interview Questions
    • Wildcard Characters
    • Distributed Database System
    • Multidimensional Database
  • TSQL Basic
    • TSQL
    • What is T-SQL
    • T-SQL Commands
    • T-SQL String Functions
    • TSQL Interview Questions
  • MariaDB
    • MariaDB Versions
    • MariaDB?list users
    • MariaDB Commands
    • MariaDB odbc
    • MariaDB Workbench
    • MariaDB for windows
    • MariaDB Server
    • MariaDB? Data Types
    • MariaDB?boolean
    • MariaDB phpMyAdmin
    • MariaDB Mysqldump
    • MariaDB Java Connector
    • MariaDB insert
    • MariaDB UPDATE
    • MariaDB? rename column
    • MariaDB AUTO_INCREMENT
    • MariaDB Timezone
    • MariaDB GROUP_CONCAT
    • MariaDB wait_timeout
    • MariaDB MaxScale
    • MariaDB? with
    • MariaDB? create?table
    • MariaDB? SHOW TABLES
    • MariaDB alter table
    • MariaDB List Tables
    • MariaDB JSON Functions
    • MariaDB Foreign Key
    • MariaDB? trigger
    • MariaDB Grant All Privileges
    • MariaDB Select Database
    • MariaDB? create database
    • MariaDB Delete Database
    • MariaDB List Databases
    • MariaDB Functions
    • MariaDB? TIMESTAMP
    • MariaDB create user
    • MariaDB add user
    • MariaDB show users
    • MariaDB Delete User
    • MariaDB? change user password
    • MariaDB? change root password
    • MariaDB reset root password
    • MariaDB IF
    • MariaDB bind-address
    • MariaDB Transaction
    • MariaDB Cluster
    • MariaDB Logs
    • MariaDB Encryption
    • MariaDB? backup
    • MariaDB Replication
    • MariaDB max_allowed_packet
    • MariaDB? performance tuning
    • MariaDB export database
    • MariaDB? import SQL
  • SQLite
    • What is SQLite
    • SQLite Commands
    • SQLite Data Types
    • SQLite COUNT
    • SQLite Boolean
    • SQLite autoincrement
    • SQLite select
    • SQLite? Bulk Insert
    • SQLite? add column
    • SQLite? concat
    • SQLite BETWEEN
    • SQLite group by
    • SQLite CASE
    • SQLite group_concat
    • SQLite array
    • SQLite? enum
    • SQLite sum
    • SQLite create table
    • SQLite Alter Table
    • SQLite Create Database
    • SQLite Delete
    • SQLite connection string
    • SQLite Database
    • SQLite Describe Table
    • SQLite Show Tables
    • SQLite exit
    • SQLite create index
    • SQLite foreign key
    • SQLite Stored Procedures
    • SQLite Extension
  • DB2
    • DB2? current date
    • DB2 purescale
    • DB2 backup
    • DB2 restore
    • DB2 C Express
    • DB2 Version
    • DB2? Architecture
    • DB2? Data Types
    • DB2? load
    • DB2? order by
    • DB2 date
    • DB2 NVL
    • DB2? update
    • DB2 warehouse
    • DB2 grant
    • DB2 database
    • DB2 VARCHAR
    • DB2? INSERT
    • DB2 LISTAGG
    • DB2 LIKE
    • DB2 TRUNCATE TABLE
    • DB2 LIST TABLES
    • DB2 between
    • DB2? current timestamp
    • DB2? length
    • DB2? bind
    • DB2 limit rows
    • DB2? export
    • DB2 with
    • DB2 Create Table
    • DB2 case statement
    • DB2 CAST
    • DB2 Functions
    • DB2 Date Functions
    • DB2? row_number
    • DB2 trim
    • DB2? Translate
    • DB2 UNION
    • DB2 timestamp
    • DB2? TIMESTAMPDIFF
    • DB2? replace
    • DB2 merge
    • DB2 COALESCE
    • DB2 ISNULL
    • DB2? explain
    • DB2 Join
    • DB2 alter column
    • DB2 rename column
    • DB2? Describe Table
    • DB2? rename table
    • DB2 List Databases
    • DB2 LUW
    • DB2 Query
    • DB2 GROUP BY
    • DB2 TO_DATE
    • View Serializability in DBMS
    • MariaDB Join
    • MariaDB JSON
    • MariaDB? show databases
    • Dataset Normalization
    • MariaDB Max Connections
    • jdbc connection
    • MariaDB GUI
  • DBMS
    • Introduction To DBMS
    • DBMS ER Diagram
    • What is DBMS?
    • DBMS join
    • DBMS Functions
    • Data Administrator in DBMS
    • DBMS Canonical Cover
    • DBMS Log-Based Recovery
    • DBMS Multivalued Dependency
    • Netezza Database
    • DBMS Concepts
    • DBMS Constraints
    • DBMS_Scheduler
    • B+ Tree in DBMS
    • DBMS_LOB
    • dbms entity
    • DBMS Foreign Key
    • DBMS Users
    • DBMS_Metadata.get_ddl
    • Relational Algebra in DBMS
    • DBMS Components
    • DBMS Features
    • DBMS Models
    • DBMS Relational Model
    • Hashing in DBMS
    • DBMS network model
    • Relationship in DBMS
    • ER Model in DBMS
    • Data Models in DBMS
    • Static Hashing in DBMS
    • Advantages of DBMS
    • dbms_output.put_line
    • DBMS Data Dictionary
    • dbms_xplan.display_cursor
    • Normal Forms in DBMS
    • DBMS helps achieve
    • DBMS 3 tier Architecture
    • Relational Calculus in DBMS
    • Serializability in DBMS
    • File Organization in DBMS
    • DBMS Transaction Processing
    • States of Transaction in DBMS
    • Functional Dependency in DBMS
    • Generalization in DBMS
    • Data Independence in DBMS
    • Lock Based Protocols in DBMS
    • Deadlock in DBMS
    • Integrity Constraints in DBMS
    • Concurrency Control in DBMS
    • Validation Based Protocol in DBMS
    • DBMS Locks
    • Normalization in DBMS
    • Transaction Property in DBMS
    • Specialization in DBMS
    • Aggregation in DBMS
    • Types of DBMS

Related Courses

SQL Certification Course

PL/SQL Certification Course

Oracle Certification Course

Footer
About Us
  • Blog
  • Who is EDUCBA?
  • Sign Up
  • Live Classes
  • Corporate Training
  • Certificate from Top Institutions
  • Contact Us
  • Verifiable Certificate
  • Reviews
  • Terms and Conditions
  • Privacy Policy
  •  
Apps
  • iPhone & iPad
  • Android
Resources
  • Free Courses
  • Database Management
  • Machine Learning
  • All Tutorials
Certification Courses
  • All Courses
  • Data Science Course - All in One Bundle
  • Machine Learning Course
  • Hadoop Certification Training
  • Cloud Computing Training Course
  • R Programming Course
  • AWS Training Course
  • SAS Training Course

© 2022 - EDUCBA. ALL RIGHTS RESERVED. THE CERTIFICATION NAMES ARE THE TRADEMARKS OF THEIR RESPECTIVE OWNERS.

EDUCBA
Free Data Science Course

Hadoop, Data Science, Statistics & others

*Please provide your correct email id. Login details for this Free course will be emailed to you

By signing up, you agree to our Terms of Use and Privacy Policy.

EDUCBA
Free Data Science Course

Hadoop, Data Science, Statistics & others

*Please provide your correct email id. Login details for this Free course will be emailed to you

By signing up, you agree to our Terms of Use and Privacy Policy.

Let’s Get Started

By signing up, you agree to our Terms of Use and Privacy Policy.

Loading . . .
Quiz
Question:

Answer:

Quiz Result
Total QuestionsCorrect AnswersWrong AnswersPercentage

Explore 1000+ varieties of Mock tests View more

EDUCBA Login

Forgot Password?

By signing up, you agree to our Terms of Use and Privacy Policy.

This website or its third-party tools use cookies, which are necessary to its functioning and required to achieve the purposes illustrated in the cookie policy. By closing this banner, scrolling this page, clicking a link or continuing to browse otherwise, you agree to our Privacy Policy

EDUCBA

*Please provide your correct email id. Login details for this Free course will be emailed to you

By signing up, you agree to our Terms of Use and Privacy Policy.

Special Offer - SQL Certification Course Learn More