Use CASE statement to assign a value to a specified field in Oracle

CASE statementInOracleRe-runningAssign a value to a specified fieldThe usage is what we will introduce in this article. First we need to create a database and add data. Then we will introduce this usage using two instances. Next we will introduce this part of content.

1. Create a data table

 
 

  
  
create table t(  
  
  
id integer,  
  
  
name varchar2(50)  
  
  
) 
 
 

2. Add data

 
 

  
  
insert into t values(1,'zhao')  
  
  
insert into t values(2,'qian')  
  
  
insert into t values(3,'sun')  
  
  
insert into t values(4,'li') 
 
 

Iii. case statement usage: assign a new value to a specified field

Example 1:

 
 

  
  
Select t. Name,
  
  
(Case t. id -- parentheses can be omitted here, And the id is changed to name
  
  
When 1 then 'zhao'
  
  
When 2 then 'Qian'
  
  
When 3 then 'sun'
  
  
Else 'lil'
  
  
End) -- Do not discard the end keyword.
  
  
From T t
 
 

Extension: assign a value to a specified field again. Another method is decode () usage.

 
 

  
  
select name, decode(id,1,'zhao',2,'qian',3,'sun','li') from T 
 
 

Example 2:

 
 

  
  
Select name,
  
  
Case
  
  
When id <= 2 then 0
  
  
When id = 3 then 1
  
  
Else 2
  
  
End "targer" -- defines an alias. Here, it is a double quotation mark.
  
  
From T
 
 

The above is the usage of the CASE statement to assign a value to a specified field in Oracle. This article will introduce it here. I hope this introduction will help you.