sql conditional statements code example

Example 1: sql CASE

/*CASE statements are used to create different outputs and is 
  used by SQL as a way to handle if-then logic.*/
  
  SELECT column_name,
    CASE 
      WHEN condition THEN 'Result_1'
      WHEN condition THEN 'Result_2'
      ELSE 'Result_3'
    END
  FROM table_name;

Example 2: end as sql

select 
case when ID in ('1', '2', '3')
then 'Jack'
else 'Jim'
end as Person
from Table.Names

select
case when ID in ('1', '2', '3')
then 'Jack'
else 'Jim'
end Person
from Table.Names

Example 3: case statement in sql

Case Statement basically
Like IF - THEN - ELSE statement.

The CASE statement goes through conditions
and returns a value when the
first condition is met and
once a condition is true,
it will stop reading and return the result.
If no conditions are true,
it returns the value in the ELSE clause.

If there is no ELSE part and
no conditions are true, it returns NULL.

FOR EXAMPLE =

CASE
    WHEN condition1 THEN result1
    WHEN condition2 THEN result2
    WHEN conditionN THEN resultN
    ELSE result
END 

-- example:
SELECT 
	CASE
      WHEN (1+6 = 6) THEN 'A'
      WHEN (1+6 = 7) THEN 'B'
      WHEN (1+6 = 8) THEN 'C'
      ELSE 'D'
	END 
FROM DUAL;

Result would be 'B' since it is the first
correct answer