EDUCBA

EDUCBA

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

DB2 case statement

Home » Data Science » Data Science Tutorials » Database Management Tutorial » DB2 case statement

DB2 case statement

Introduction to DB2 case statement

DB2 case statement is available in IBM which helps us to make the use of conditional behavior. The case statement works similar to the if-else statement in the coding languages. There are two types of case statements supported by DB2 which are simple case statement and the searched case statement. Both the case statements work in a similar manner and help to implement multiple expression evaluation and comparison based on which the result set can be modified. We can make use of case statement anywhere in our query as it is an expression. Hence, case statement can be used inside the SELECT statement, WHERE clause, GROUP BY clause, and even inside the HAVING clause of the query statement.

In this article, we will study the general syntax of the simple case statement and searched case statement and we will also study the implementation of this statements along with the examples in DB2 database management system.

Start Your Free Data Science Course

Hadoop, Data Science, Statistics & others

Simple Case statement:

Simple case statement comes with multiple optional WHEN clause which helps us to mention multiple possible cases of the expression that is passed to it according to which the Let us firstly see the syntax of the simple case statement which is as shown below-

CASE exp
WHEN exp 1 THEN selected output 1
WHEN exp 2 THEN selected output 2
...
WHEN exp n THEN selected output n
[ ELSE output for else] END

In the above expression, exp 1, exp 2 are the expressions that will evaluate to a particular value. The evaluated value of the expression is matched with exp and then accordingly the selected output for that value is given as the output result. In case none of the expression gets matched then if specified the output for else mentioned after ELSE clause is considered as the final output of the select statement.
If all the expressions fail to match and we have not specified the ELSE clause as well then, a default NULL value is returned from the case statement. Most of the times, we make use of ISNULL or COALESCE function to handle the NULL values returned by the case statement.

Let us consider one example of the simple case statement. We have one tale named Sales_Customers which contains the values as shown in the below output of the following query statement:

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 (8,668 ratings)
Course Price

View Course

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

SELECT * FROM [Sales_Customers];

DB2 1

Now, suppose that we have a condition that if the mobile number begins from 914568524 having all the nine characters as mentioned then we have to retrieve the mobile number value else we have to retrieve an encoded mobile number with ********** value as the output. In this case, we can make the use of a simple case statement by specifying 914568524 as the expression in string format, and the WHEN clause will contain the substring function to get the first 9 characters of the mobile number field.

SELECT CASE "914568525"
WHEN SUBSTRING(mobile_number, 1, 9)
THEN mobile_number
ELSE "**********" END
as "Mobile Number"
FROM [Sales_Customers];

The execution of above query statement gives out the following output containing all the mobile numbers that have “914568525” string in the beginning and “**********” in case if the expression doesn’t matches the substring of mobile number field value as shown below –

Number of records

Searched case statement:

In case of searched statement, we do not go for matching the expression values with the other expressions mentioned inside the WHEN clause of the CASE statement instead the expressions that are mentioned in the WHEN clause needs to evaluate to a Boolean value. If any of the expression evaluates to true the search or execution of the case statement stops there itself and the output mentioned after that corresponding when clause is considered for the final output of the case statement.

If none of the expression evaluates to true then the case statement returns NULL as the output. If we don’t want to show NULL values as the output then we have to make use of ISNULL, IFNULL, or COALESCE functions to handle NULL values and display any of the alternative value in that place.

The syntax of the searched case statement is as shown below-

CASE
WHEN exp 1 THEN selected output 1
WHEN exp 2 THEN selected output 2
...
WHEN exp n THEN selected output n
[ ELSE output for else] END

Just the difference between simple and searched statement is the mention of the expression after CASE clause for matching. Let us now consider one example of the searched CASE statement. Consider the same previous case where we were trying to display the mobile numbers only when the begin with a particular string value with which we are evaluating using LIKE statement which will return a Boolean value as soon as it gets true it goes for retrieving the column value of mobile_number else it fetches “**********” which is used to represent encoded string if expression evaluates to false. Our query statement will now look as shown below –

SELECT case
when mobile_number like "914568524%"
then mobile_number ELSE "**********"
END
as "Mobile Number"
FROM [Sales_Customers];

DB2

The output of the above query statement is as shown below which is same as that of while using the simple case statement.

Conclusion

We can make the use of case statement to induce if-else or conditional behavior in our query statements. There are two type of case statements which are simple case statement and searched case statement. In a simple case statement, we have to find out the matching expression value for all the specified when clauses and then for the matching WHEN clause the THEN clause is given as output else it goes for giving out the expression value mentioned in ELSE if specified else it gives NULL value. In case of searched case statement, we have to specify the expressions after WHEN clause such that they will evaluate to a Boolean value. The expression whose value gives true is considered for the final output else it goes for giving expression after ELSE clause if specified else NULL value.

Recommended Articles

This is a guide to DB2 case statement. Here we discuss the Introduction, syntax, examples with code implementation. You may also have a look at the following articles to learn more –

  1. DB2 LISTAGG
  2. What is DB2?
  3. DB2 Interview Questions
  4. Data Warehouse Software

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
  • 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
  • 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
  • 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
  • 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 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
  • DBMS
    • Introduction To DBMS
    • DBMS ER Diagram
    • What is 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