switch case sql column

1SELECT CASE lower(col1)
2	WHEN 'agree' THEN 'Ok'
3	WHEN 'disagree' THEN 'Ko'
4    ELSE
5        CASE 
6            WHEN col2 = 1 THEN 'Ko'
7            ELSE 'Maybe'
8        END
9END AS my_result
10FROM table_name;

1-- Case Eg.) to retrive the MAX value of a Field 
2-- if there are entries for the Field in table MAX value will be returned 
3-- But if there is no entries at all for the Field in tabel MAX will return
4-- Null as the output. But Using Case When we can check it out return zero 
5-- or any other value if there is no enties for the Field in table..
6SELECT 
7CASE   -- Like Switch Case
8	WHEN -- First When condition 
9		(MAX(BILLID) IS NULL) -- Condition 
10	THEN 1   -- output   (We can also add more When conditions like Above)
11ELSE -- When WHEN Condition not Satisfied Below will be Executed. 
12		(MAX(BILLID)) -- output
13END 
14as MAXBILLID   from  DUAL;
15-- Final Output
16-- If there is no entry in the Field for the table
17-- BILLID
18--  1
19-- If there are entries MAX of that Field value from the table
20-- BILLID
21-- 10