fucntion with if else in sql code example

Example 1: sql if else

-- PL/SQL
BEGIN
    IF my_val = 1 THEN [...]
    ELSE [...]
    END IF;
END;
-- In a query (DUAL is for Oracle)
SELECT CASE WHEN my_col = 1 THEN 'Ok' ELSE 'Ko' END AS my_result
FROM DUAL;

Example 2: t-sql if else

IF 1=1
	SELECT 1
ELSE
	SELECT 0
-- returns 1

-- Definition
IF Boolean_expression   
     { sql_statement | statement_block }   
[ ELSE   
     { sql_statement | statement_block } ]