如何在Oracle中使用'CASE WHEN‘语法？

CASE
    WHEN condition1 THEN result1
    WHEN condition2 THEN result2
    ...
    ELSE resultN
END

SELECT column_name,
       CASE
           WHEN column_name = 'value1' THEN 'Result 1'
           WHEN column_name = 'value2' THEN 'Result 2'
           ELSE 'Other Result'
       END AS result
FROM table_name;

SELECT category,
       COUNT(*) AS count,
       CASE
           WHEN COUNT(*) < 10 THEN 'Low'
           WHEN COUNT(*) >= 10 AND COUNT(*) < 20 THEN 'Medium'
           ELSE 'High'
       END AS group
FROM table_name
GROUP BY category;

UPDATE table_name
SET column_name = 
    CASE
        WHEN condition1 THEN value1
        WHEN condition2 THEN value2
        ELSE valueN
    END
WHERE condition;