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 ID ELSE use IDParent

Is there a way to use an If Else like condition in SQL to return only single value?

Answer 1

you can use CASE

SELECT   ...,          CASE WHEN IDParent < 1 THEN ID ELSE IDPArent END AS ColumnName,          ... FROM     tableName 

Answer 2

Here, using CASE Statement and find result:

select (case when condition1 then result1              when condition2 then result2              else result3              end) as columnname from tablenmae: 

For example:

select (CASE WHEN IDParent< 1 then ID               else IDParent END) as columnname from tablenmae