How to write the following CASE statement

Question

I need to calculate Retainer amount. The derivation of it is as follows:
"A fixed value of 10000 per month for employees who have served for less than 2 years and 15000 for more than 2 years. This increment will be affected in two cycles a year, in the January or July."
The years of service can be calculated using date_of_joining.

Answer 1

Use this logic
SELECT DECODE(SIGN(SYSDATE - ADD_MONTHS(HIREDATE,24)),-1,10000,1,15000) from <table_name>Is this you need
In every Jan/July month employee get a Sal+Fixed allownce (10000 if less than 2 years in company/15000 if more than 2 years). In other month they get just the salary
SELECT CASE WHEN TO_CHAR(SYSDATE,'MM') IN ('01','07') THEN
               CASE WHEN SYSDATE- ADD_MONTHS(HIREDATE,24)> 0 THEN
                    SAL+15000
                ELSE
                    SAL+10000
                END
        ELSE
          SAL
        END  SAL
FROM EMP
/Edited by: Lokanath Giri on १७ सितंबर, २०१० ४:५६ अपराह्न