Using If else in SQL Select statement

Question

I have a select statement which will return 2 columns.

ID | IDParent

Then in my program I have to test if IDParent is < 1 then use

Answer 1

sql server 2012

  with
  student as 
(select sid,year from (
values (101,5),(102,5),(103,4),(104,3),(105,2),(106,1),(107,4)
) as student(sid,year)
)
select iif(year=5,sid,year) as myCol,* from student


 myCol  sid year
101 101 5
102 102 5
4   103 4
3   104 3
2   105 2
1   106 1
4   107 4

Answer 2

select 
CASE WHEN IDParent is < 1 then ID else IDParent END as colname 
from yourtable

Answer 3

SELECT CASE WHEN IDParent < 1 
            THEN ID 
            ELSE IDParent 
       END AS colname 
FROM yourtable

Answer 4

Here is some example using CASE WHEN

SELECT 
    CASE WHEN A > 1 THEN
            'Greater than 1'
    END  
FROM TRIANGLES

.

SELECT 
    CASE WHEN A > 1 THEN
            A
    END  
FROM TRIANGLES

.

SELECT 
    CASE WHEN A > 1 and B > 1 THEN
            'Greater than 1'
    END  
FROM TRIANGLES

.

SELECT 
    CASE WHEN A > 1 THEN
            'greater than 1'
         ELSE
            'less than 1'
    END  
FROM TRIANGLES

.

SELECT 
    CASE WHEN A > 1 THEN
            'greater than 1'
         ELSE CASE WHEN A >= 0 THEN
                      'greater than or equal 0'
                   ELSE
                      'less than 0'
              END        
    END  
FROM TRIANGLES;

Hope this helps

Answer 5

Here are two ways "IF" Or "CASE".

SELECT IF(COLUMN_NAME = "VALUE", "VALUE_1", "VALUE_2") AS COLUMN_NAME 
FROM TABLE_NAME;

OR

SELECT (CASE WHEN COLUMN_NAME = "VALUE" THEN 'VALUE_1' ELSE 'VALUE_2' END) AS COLUMN_NAME 
FROM TABLE_NAME;