sql - Oracle - 更新、解码和设置值

Question

我有一张桌子，例如

**Fruit   Number**
Apple     5
Grape     9
Orange    1
Coconut   54
Mango     22

我想要 ：

1. 选择整个列表
2. 将“苹果、芒果、椰子”放在列表顶部。
3. 更新当前订单，其中 number = rownum

该列表应如下所示：

**Fruit   Number**
Apple     1
Mango     2
Coconut   3
Grape     4
Orange    5

我尝试了以下但遇到语法问题..

update tablename 
set id = rownum
where fruit in (select fruit from table order by decode(fruit,'Apple',1,'Mango',2,'Coconut',3))

Answer 1

UPDATE (
    SELECT ROWNUM+5 AS r, fruit, number FROM TABLE
    WHERE fruit NOT IN ('Apple', 'Mango', 'Coconut', 'Grape', 'Orange')
    UNION
    SELECT 1 AS r, 'Apple' AS fruit, number FROM TABLE
    UNION
    SELECT 2 AS r, 'Mango' AS fruit, number FROM TABLE
    UNION
    SELECT 3 AS r, 'Coconut' AS fruit, number FROM TABLE
    UNION
    SELECT 4 AS r, 'Grape' AS fruit, number FROM TABLE
    UNION
    SELECT 5 AS r, 'Orange' AS fruit, number FROM TABLE
) 
SET number = r;

Answer 2

以下查询将为您执行此操作。

UPDATE table SET number =
CASE fruit
    WHEN 'Apple' THEN 1
    WHEN 'Mango' THEN 2
    WHEN 'Coconut' THEN 3
    WHEN 'Grape' THEN 4
    WHEN 'Orange' THEN 5
END;