Oracle 21c

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CREATE TABLE ABC_TABLE ( 
Currency VARCHAR2(10) ,
Amount     NUMBER,
Amount_CNY  DECIMAl(10,2) GENERATED ALWAYS AS ( CASE WHEN Currency ='EUR' THEN (Amount/0.14 ) 
                                                    WHEN Currency ='USD' THEN (Amount/0.13 ) 
                                                    WHEN Currency ='GBP' THEN (Amount/0.12 ) 
                                               END ) VIRTUAL);
INSERT INTO ABC_TABLE (Currency,Amount)
  SELECT 'EUR',100 FROM DUAL UNION ALL
  SELECT 'USD',300 FROM DUAL UNION ALL
  SELECT 'GBP',200 FROM DUAL;
3 rows affected

SELECT *
  FROM ABC_TABLE;


CURRENCY
AMOUNT
AMOUNT_CNY


EUR
100
714.29

USD
300
2307.69

GBP
200
1666.67